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EMPLOYEE BUILD: ART’S 2004 SUBARU FORESTER XT: The Re-buildening (Part 1)

It’s only been about four months since I closed the book on my Forester build. My May deadline was met and I finally got my chance to enjoy the car, and enjoy it I did. All the brake and suspension upgrades allowed me to drive it more like an STI than a Previa (another big shoutout to Whiteline for that) and the wheels and exterior bits had me falling in love with the look of the old toaster-box all over again. I was, and still am, satisfied with what this car has become and distinctly remember leaving off my last build blog with this statement:

“So there it is, the car is totally, completely, unequivocally done…There’s a few [small] changes I’ll be making and ironing out some little issues here and there, but for the most part I can finally put down the wrenches, close the wallet, and enjoy staring at it for a while.”

What I ultimately meant by that was: “no way in hell I’m putting this thing back up on jack stands this year, I’m done, I’m finished, no thanks”…well, the wrenches are officially back out, the wallet is all but drained, and it’s go-time once again.


Given my budgetary build constraints I normally have to look for opportunity to present itself before taking on something new. That’s why I never really plan the projects I do, but wait for them to fall into my lap; often times at the most inopportune moments. Some weeks ago, an opportunity came in the form of one friend’s frustration over his project car. His original intent was to build a sleeper FXT that would blow the doors off mostly anything in his path, but unfortunately his first go-around was less than successful thanks to a cam issue in his newly built motor. By the time the blame was placed and the logistics of the rebuild were ironed out, he had lost interest in his original plan. We got talking and long story short, although I wasn’t ready to take on a new project, I showed up to his place with a  stack of cash and drove off with a familiar addition to my stable:


In the next post I’ll give you a rundown of what the new FXT is all about, but the most important bits are its..drum roll…JDM 6spd drivetrain and sleeved motor, among a bevy of other go-fast parts. [I’ll also be showing you a little update on my garage and include a few pictures of the other Forester in all it’s current glory].

I always had the intention of yanking out the original motor in my FXT, picking up a pre-assembled IAG shortblock, building the heads, and switching over to E85. Along with the bolt-on’s and turbo I already had on the motor, pushing out 400-450WHP would’ve been very achievable. When I sat down to crunch the numbers of the longblock build, factored in a 6spd drivetrain, and added up the endless miscellaneous costs, the build was all but unattainable, so the idea was put on hold.  Now that dream is back in full force. What really makes this entire build possible is the fact that I am starting out with two perfectly running, identical Foresters, and ending up with [hopefully] two perfectly running, identical Foresters. That means that one will be will eventually get sold to recoup some of the costs of the build and the other will remain mine-all-mine, becoming as close to my dream car as I could have hoped for.

So here we go. The initial plan is to swap over the rear ends of the cars, dropping both subframes and doing an exchange. Although the new FXT has Brembos all around, I’m planning on keeping the rear and front hub/brake setups just the way they are on the old FXT since they were just freshly rebuilt with new bearings, seals, extended studs, powdercoat, etc.


Once that’s done and I’ve got two rolling vehicles again, I’ll be pulling the engines and transmissions out of each. Some new gaskets, a bit of cleaning, and they’ll get thrown back into their doppelganger’s chassis’ and all will be right with the world. Nice and simple; on paper anyway, but judging from past builds it will be anything but.

This time around I plan to record the build on video so be sure to follow me on Youtube and Instagram @thenotorious_a_r_t for project updates. For those that need a brush-up on the last build, check out my original blog posts here:

As promised, albeit a bit late, I’ll leave you with a small collection of photos courtesy of Cody Helton (@chelton91). Props go to him for making my car look better in photos than it ever could in person:






-Art Petrakov

Employee Build: Alex’s 2003.5 Turbocharged Infiniti G35 Drift Sedan (Part 2)

Employee/Author: Alex Docken

Editor: Art Petrakov

When I last left off, I was discussing some of the changes that are taking place on my G35 for the upcoming drift season.  As we speak, Nathan Chin at Metal in Motion in finalizing the exterior bodywork and the car is just about ready to get picked up. I absolutely can’t wait to have it all put back together and see this phase of my vision for the car completed! These particular changes are something I had originally hoped to have done last year, but with the crazy amount of fabrication taking place and with how ever-changing car deadlines can be, the big debut was put off until 2017. There is still a laundry-list of things I hope to get done to the car, but that will just have to wait for later on this season, or next.

While the car has been over at Nathan’s, I haven’t had much opportunity to get my own hands dirty on it. Instead, I had a chance to start putting together Youtube content to chronicle the build and the upcoming drift season. I’ve also been busy with drift-event planning and working on design aspects for team apparel, stickers, etc. Recently, I was also lucky enough to be able to spend some time in California for Formula D Long Beach. The event was an unreal experience and gave me a chance to hang with some old friends and meet some new. While out there, I was able to make it to the Hardcore Japan X Super Street Meet, as well as the Hoonigan Donut Garage After-Party, which were both an absolute blast.

Alex California Trip

Alex California Trip 2

Alex California Trip 5

Alright, back to the car!

I’ve always LOVED this style of sideskirt extension, but it was proving very hard to source the ones I wanted, let alone find them in a length that was appropriate for my chassis. I tried several options, including ChargeSpeed Subaru Impreza Extensions, but in the end, I had to settle with the more appropriately-fitting Outcast Garage Skirt Extension. After some research and sourcing of parts, I was able to find some authentic URAS Side Skirt add-on’s (basically just the flare piece). I brought these over to Nathan and he modified them to be the exact fit and finish I was looking for!

G35 Skirts and Extensions

In addition to the skirts, I also dreamed of equipping the car with a set of front bumper canards. These are readily available for cars like the S13/S14 240SX, which have a longer front bumper and less curve than the G35, but the choices for me were few and far between. What I ended up doing was sourcing some ORIGIN Front Canards and had Nathan modify them to fit perfectly with the curvature of the bumper. We also created some custom metal upper canards based off different styles I liked on other cars, with a bit of our own flare…

@chelton91 @extendedclipproductions
@chelton91 @extendedclipproductions

Two other big aesthetic changes had to do with the hood and mirrors. I’ve had aftermarket Ganador-style mirrors for years but hadn’t gotten around to modifying them to fit the chassis until last fall. I had Nathan smooth and mold a set of custom mounting plates that I created for a truly OEM look, as opposed to the roughly-fabricated way I dropped them off in. I’m very excited to have aggressive aero mirrors on the car, since I think mirrors can make a major difference to the look of a build. Aside from that, the look of the hood has always been something that’s bothered me. Last season was a mad dash to catch as many events as possible and with the build taking much longer than first anticipated, the hood was a last minute temporary solution. This year, I am looking to have the hood match more of the look I had originally intended, while functioning to properly flow air through the engine bay in conjunction with the v-mount setup. Expect to see the finalized design in my next post!

@chelton91 @extendedclipproductions
@chelton91 @extendedclipproductions

Another change I had mentioned to make in my last post was the brakes. At the time I was torn on what route I wanted to go, but after having some friends deal with bracket adapter issues on different brake conversions, I decided to keep things simple with the OEM-offered Brembo brakes. In addition, I picked up the Stoptech Sport Upgrade Kit which included stainless steel lines, slotted rotors with black painted centers, and sport pads to compliment the rebuilt Brembo calipers. My factory brakes have always functioned just fine for the car’s intended purpose, so in my mind anything crazier than upgrading to the OEM Brembos seemed a bit overkill.

So that’s where I am at! If all goes to plan I’ll be picking up the car today or tomorrow to start finishing up the final touches. I have some small updates/changes to make in the engine bay, as well as installing the aforementioned brakes, swapping all fluids, tires, and getting the car ready for Wekfest Chicago. I hope to see and meet some of you there! Otherwise, the week after, I will have the car at GrimmSpeed’s first-ever meet at our shop on May 5th and will be attending Cars and Coffee and potentially the MNCEC meet on May 6th/7th, respectively.


Come find me at any of these events and feel free to say hello and ask questions. I’m always wanting to get to meet people and help anyone out with their own build. I can’t wait to see what 2017 brings as well as to share it all with you!


IG @DabSedan







2015 Ford Mustang – Air Lift Performance – Part 1


We know what you’re thinking. “GrimmSpeed, you stand for detailed, meticulous engineering and high-end performance – what are you doing messing around with air ride stuff?” We know that’s what you’re thinking, because it’s what we were thinking, too. With that said, just as important to us as engineering and performance are experimentation, innovation and discovery. As those three things are what brought us to pursue the Mustang Ecoboost market, we thought it only fitting to continue on that theme and see what this air ride business was all about.

Our goals for the GrimmSpeed shop car were two fold. The first and most important is that it was to be used as a tool for the development of the GrimmSpeed product line. The second was to explore a new area for ourselves, learn more about the car and create something that’s interesting. We had no idea that the two would so easily mix.

At GrimmSpeed, whether it’s drag, track, drift, autox or show, we’re all car guys. We like to keep on top of major trends and form educated opinions – it’s part of what helps us communicate with our customers. In the Subaru world that we come from, internet broscience 101 clearly states that air suspension sucks because some other guy says so. Fortunately for you, we prefer to learn lessons the hard way. It was with this crazy idea that we got to work procuring an Air Lift Performance kit with their V2 management for our Mustang.

The Kit

Our shipment was delayed a few days, as the Mustang kit has been already been very popular for Air Lift. Upon arrival, I could barely get a single photo taken before the team tore into the boxes.


The first thing that we took note of was the excellent packaging. As a manufacturer ourselves, we know that shipping heavy and valuable items safely can be a challenge and that the design process for those products isn’t over until we have packaging prepared as well. Air Lift clearly takes the same care in this area as we do, because everything arrived in excellent condition.


The first box that we opened contained the compressor, AutoPILOT V2 components, the necessary wiring harness and a generous length of nylon tubing. The fit and finish of the AutoPILOT hardware far exceeded our expectations, not because we didn’t believe that Air Lift made quality parts, but because electronics like this often feel junky, even if they work just fine. Not the case here. The manifold feels extremely well made, with a billet aluminum lower and an injection molded cover. The handheld controller feels similarly substantial, but a nice rubberized coating and buttons that click firmly when depressed.


The VIAIR compressor and all included fittings and tubing, while not quite as exciting, seem to be of the same quality. We really like that Air Lift includes a tubing cutter with the kit, to ensure that we get square cuts and don’t need to spend time troubleshooting that common issue after installation. We opened the rest of the boxes to ensure that the tank, front and rear assemblies were all present before we got started. The front and rear assemblies are exactly what we expected, having seen the quality of the V2 management hardware. The front struts look similar to most familiar coilover setups, but with a bag instead of a spring. The Air Lift S550 Mustang kit comes with integrated front camber plates that are beautifully machined with a red anodized finish. The rear back setup is a bit different, with a standalone bag assembly with features that capture the top and bottom once installed, to ensure that the bag stays in place. We gave each assembly, front and rear a quick inspection to make sure we didn’t see any obvious defects that would give us trouble down the road (we didn’t).




We’ll breeze through installation relatively quickly, as Air Lift has it very well documented in their manuals, which are printed in nice booklets and included with their products. The first thing that we did was get the tank mocked up under the parcel tray in the trunk and drill holes in the tank brackets and the tray in order to mount the tank exactly where we wanted it. There may be alternative mounting solutions that wouldn’t require drilling holes, but we’d prefer to spend the time and effort up front so that we can enjoy the finished product more later on. Retaining trunk space was important to us, so tucking the tank against the rear seats was an excellent solution.


Next up was mounting of the manifold, wiring and running air lines. We mounted the manifold in a convenient spot above the tank using the included self-tapping screws. One installation note here is that the screws will not slip through the holes in the V2 manifold – you’ll need to allow them to tap the machined holes while they pass through. We used a cordless impact to do this, which saves your wrist and goes very quickly. This ‘interference fit’ made perfect sense after we got everything in place, as once mounted, the manifold was mounted very securely and wouldn’t shift around.


We mounted the compressor in the spare tire area; since our Mustang didn’t come with a spare, it was a perfect fit. The lines off of the compressor are relatively short, so we made a harness that allowed us to easily extend the wiring to the AutoPILOT harness. We went a little overboard (as we do here at GrimmSpeed from time to time), but most DIYers would have no trouble crimping some connectors to do the same. Just be sure to use the proper gauge wire.


Now for the fun part. We ran the airlines to the front, first. With the back seats folded down, removing the plastic interior bits was actually quite easy. We tucked the front lines down each side of the car, just under the carpet with the rest of the factory wiring harness.  In the front on both sides of the car, is a nice rubber grommet with a small nipple on it that’s unused (see photo). We clipped the end of that nipple off (from the wheel well) and then fished a piece of welding wire into the cabin, so that we could locate the grommet and pull the airline back through. It was a tight fit, but that’s how we know it’ll be sealed nicely from the elements here in Minnesota.


With the airlines up front, we went ahead and installed the front strut assemblies. One thing to note is that camber adjustment appears to be very difficult from the engine bay once the struts are in place, so make your best approximation before installation. This is also the time to set your ride height, so be sure to follow Air Lifts instructions in doing do. One thing that we noticed immediately while handling the front struts is how much lighter than the factory equipment they were. Our initial assumption was that the air ride would be heavier, but it seems that the lack of steel springs might more than compensate for the added compressor, tank and management.


The rear setup requires a little bit of basic assembly prior to installation. Here is where I was able to find one of only two very small issues during installation. The steel perches that are to be bolted to each bag have a plate welded inside of them that would block a socket from reaching the head of the bolt. Air Lift was kind enough to add clearance for a tool in this area, but because the plate is welded at an angle, I was still not able to get a socket onto the bolt without it getting stuck. Perhaps it was just my socket, but in any case, it was quite easy to just use a standard box wrench.


Bolting the bag into place was where I got stuck again, as the manual instructs you to align a feature on the bag assembly with a notch in the upper spring perch. Our car didn’t have that notch and although I was sure I’d be able to approximate its location, I called Air Lift’s support line anyway. I was very quickly directed to somebody that was able to answer my question and got right back to work – awesome customer support!


Booya! All struts, shocks and bags are in place, air lines are hooked up and secured such that they won’t be getting in anything’s way while we thrash on our Mustang and we’re ready to rock. I filled the tank using our shop air compressor to save time and let the auto calibration do its thing. After that, we swapped to our Velgen wheels and Mickey Thompson tires, which are a much more aggressive fit, and dialed in our presets.


The wheel setup currently on the car is a 20×10.5 in the rear and a 20×9 up front. Tires are Mickey Thompson Street Comps in a 305/35/20 and a 255/35-20. We’re able to air the car out completely without any modifications to the fenders or wheel wells and the fender liners are still in place.



Here’s the fun part – performance. The word ‘performance’ can have a number of different meanings and we’ll attempt to cover each of them here. First of all, the performance of the Air Lift Performance kit, with respect to how well it functions, is excellent. We’d never worked with an air ride setup before, but with a careful installation, we were up and running with zero issues. The AutoPILOT management is just sophisticated enough to offer multiple preset ride heights and other features, but is simple enough that it should be very reliable.


Having put a thousand miles or so on the car since the installation, our definition of performance, given our intend use for the car, is how well it performs all of the tasks that are required of it on a normal day. We have the preset bag pressures at a height that is perfect for driving around town, but if we find ourselves needed to drive into steep parking lots or onto a dyno, two button clicks are all that’s required to lift the car above stock height. Two more button clicks after you’ve parked at a local GTG and the car’s stance commands attention and curiosity from everybody around. Equipped with the Air Lift kit, our Mustang does absolutely everything that’s asked of it on a daily basis.

We had the opportunity to rent out a local test track and spend the day beating on the car. The purpose of this was primarily to test some of the product offerings that we’ve been developing, but the added bonus was a full day of putting the Air Lift system through its paces. It was only a couple of laps before I entirely forgot that there was anything ‘abnormal’ about the suspension on the car. It felt firm, handled beautifully and to an enthusiast racer like myself, the car didn’t seem any more or less prone to being upset by sudden changes in direction, bumps in the track, etc.


None of us are professional race car drivers and none of us are ‘bout dat static life’. We consider ourselves to be pretty normal, open-minded car guys. We approach evaluation of our products and others with the goal of providing constructive criticism in order to help improve. In the case of the Air Lift Performance kit on our 2015 Ford Mustang Ecoboost, for our purposes, it’s nearly perfect.



GrimmSpeed EFR7163 Twinscroll Turbo Kit Development

The time has finally come to let the cat out of the bag on GrimmSpeed EFR7163 Twinscroll Turbo Kit development! We’ve been developing this system alongside our top mount intercooler since late last summer. The initial purpose was to build a single car that would produce big turbo power, but with responsiveness that’s similar to factory. This car would be an excellent test bed to prove that our TMIC would support big power with killer responsiveness, without sacrifice. We selected the Borg Warner 7163 Twinscroll Turbo for this project and immediately got to work with the design of a truly equal length header.


We quickly realized why nobody else is doing this. The configuration of the twinscroll ports on an aftermarket turbo is rotated 90 degrees from the factory turbo, making the routing of an equal length manifold below the car extremely difficult. We had to leverage all of the engineering tools and technology that we have access to in order to design a manifold that would fit the turbo that we selected without losing usable ground clearance and veering from our equal length requirement. The firing order of the motor dictates the runners that need to be paired for the twinscroll turbo to function properly, but it’s not even that simple. It’s not our style to hack something together that fits and works – we optimize. Finally, in such tight quarters, it’s also critical to figure out if a given manifold design can be fully welded and if there is adequate room for bolts/studs/nuts and tools needed for installation.

GrimmSpeed FA Header 3 GrimmSpeed FA Header 10

FARO arm 3D scans of the underside of the car and of the factory manifold and turbo gave us a very good idea of the space that we had to work with. We experimented with three different collector designs and five different runner concepts before settling in on the one below. We were able to design a collector and runners in Solidworks that offered truly equal length (variance between runners is only 2.3%). Because we were concerned with ground clearance, we removed the EFRs IWG (internal wastegate) and used a pair of external wastegates. Knowing what we know now, our plan will be to utilize the EFR’s IWG on production kits if/when the project reaches that stage.

GrimmSpeed FA Header 7 GrimmSpeed FA Header 5

For this design, we knew that we needed a perfectly symmetrical collector to help us achieve the performance that we’re targeting and utilize the full potential of the twinscroll EFR turbo. The way that the runners pair up and enter the turbo is critically important, so despite the tight space constraints that we’re working with, we made no sacrifice in the general collector design.

The best that we could fit is still a bit steeper than we’d have preferred, but we’re working with hard limits here. This collector has a 45 degree merge angle. Being that the turbo that we’ve selected uses a divided T4 turbine housing, that’s the size flange that we’ll use. Of course, it’s helpful that GrimmSpeed also manufactures the highest quality T4 gaskets around!

GrimmSpeed FA Header GrimmSpeed FA Header 2


Our engineering team and fabrication team worked together to prototype the kit with great accuracy. We were able to use a very slightly modified GrimmSpeed StealthBox Intake and a very slightly modified GrimmSpeed J-Pipe. For charge air cooling, we used a GrimmSpeed prototype charge pipe and prototype TMIC. The charge pipe is quite simple, as the EFR7163 has a bypass valve built into its compressor housing. After welding was finished and the pipes became cool, what we ended up with was a thing of beauty:

GrimmSpeed FA Header 8

Getting coolant and oil through the turbo just took some clever routing of hoses, since the factory turbo already uses both in the same location. For the turbo oil pan, we were able to simply reuse the factory oil pan, mounted directly to the turbo. Production kits will very likely include a smaller, custom pan, but that’s yet to be determined.

GrimmSpeed FA Header 9


We need to start with a shout out to DB Performance in Rogers, MN. We really enjoy the opportunity to bring our cars to a third party shop for dyno testing and tuning. We think that it helps us maintain a level of transparency in a world where closed-door dyno testing is so common and we love having a second set of expert eyes on the work that we’re doing. Shane, Danny and the rest of the crew run a top-notch operation and if you’re in the area, we highly suggest that you check in with them regarding maintenance, modification and tuning. These guys build some serious cars.

With the kit finally on the car, we knew a few things. We knew that fueling would limit our ability to make power. Our intention is to run the car on E85, so we’ll need a supplementary fuel system to deliver the volume of fuel that we’ll need to push this kit. We also knew that the kit would produce power and torque in excess of the limits of the factory motor. A phone call to our friends at IAG Performance for their Stage 3 shortblock and 14mm head studs solves that problem with ease. At the same time, we’ll have the heads gone through before putting it all back into the car. Other supporting modifications will be made at the same time (clutch, mounts, etc).

Step one, though, was to get the car to the dyno for some shakedown pulls and to build confidence in the kit before pulling the car apart for motor/heads/fueling. We pumped the 93oct out of the tank and replaced it with MS109. The thought was that this would help us safely and repeatably push the kit a little bit farther on the dyno than 93oct and E85 would allow with the factory fuel system. Our goal here was to determine that the cooling and oiling of the turbo was working flawlessly and to prove that the complexity of the manifold was justified by the increased performance offered in terms of spool and power production. The car was tuned by Shane at DB Performance (Rogers, MN) with the COBB Accessport.

2015 Subaru WRX, 6MT, 9000mi

  • GrimmSpeed EFR 7163 Turbo Kit
    • Borg Warner EFR 7163 Twinscroll Turbo
    • GrimmSpeed EL Manifold
    • Turbosmart Compgate 40 EWGs (pair)
    • GrimmSpeed J-Pipe (modified)
    • GrimmSpeed Stealthbox Intake (modified)
    • GrimmSpeed Big Turbo EBCS
    • GrimmSpeed Charge Pipe
    • GrimmSpeed Top Mount Intercooler w/ splitter
  • STOCK Catback Exhaust
  • STOCK Fuel System

Dyno: Dyno Dynamics
Stock 2015 WRX Baseline: 166whp/181wtq
Fuel: MS109

GrimmSpeed FA Header 11


Our first dyno session with this kit went even better than we had hoped. We kept very conservative, as the goal wasn’t to make power, but to prove that the setup functions properly. The coolant and oil feed and return for the turbo worked flawlessly on the dyno for 7hrs, which was one of our primary concerns, given the compact space.

Our primary goal for this kit was to provide a driving experience that isn’t unlike a stock turbo car, but with a power curve that leaves nothing to be desired. To achieve that, we knew we needed a turbo that could spool extremely fast but with the potential to produce really healthy power. This preliminary test was to prove the first part, as we’re quite confident in our ability to achieve the second. As the chart below shows, the GrimmSpeed EFR7163 Twinscroll kit spools just 200rpm slower than a ‘stage 2’ stock turbo car, hitting 15.5psi@3000rpm and 19.5psi@3500rpm as it approaches its target boost. With E85 and higher boost targets, we expect even faster spool, but these results alone are more than enough to demonstrate the capability of this beautifully designed turbo manifold paired with a killer EFR twinscroll turbo.

GrimmSpeed FA Header 12

Although making power wasn’t part of the goal, we know it’s on everybody’s minds, so we’ll share anyway. As you can see this car, in 100% stock form, produced 166whp on the dyno at DB Performance (known for reading very low). With the EFR7163 kit at only 20-21psi and relatively conservative tuning, the car was making 320-330whp and 300-310wtq. On our local dynojet, that equates to a ballpark 400whp/390wtq. The strange behavior at the top of the chart can likely be attributed to the fact that the car isn’t setup to make power (stock catback, for example) and some fuel/spark issues that we’ll sort out when we come back ready to turn it up.

What’s next?

We’re waiting for the weather to get into the 40s next week so that we can run the car on the road and do some logging and 2015 TMIC testing before we pull it apart for the following:

  • IAG Performance Stage III Short Block w/ 14mm head studs
  • Headwork/valvetrain
  • Supplemental fueling so that we can run E85
  • Water-meth
  • Capable clutch
  • Catback exhaust
  • TGV delete
  • Data acquisition hardware/sensors

Then we’ll be back to the dyno to push the car and find its limits. That’s all we’ve got for now! As many of you know, this project is also a way for us to push our 2015+ WRX TMIC pre-production units to their limits (maybe?). We’ll keep you updated on that front as well, but all we’ll say for now is that they’re keeping up with this kit very nicely so far.

Winter Mode – Rally Armor UR Mud Flaps

It’s not very often that we go out of our way to give a tip of the hat to another manufacturer’s product, but from time to time, there’s a product or service that we feel is deserving of our praise. This week, that product is from Rally Armor and it’s their model-specific urethane mud flap kits. At GrimmSpeed, we pride ourselves not only on engineering top-notch products, but also on creating an experience for the user that is second to none and that’s exactly what Rally Armor has done with these kits.


Here in Minnesota, it’s no secret that our winter months can be devastating to a car. The roads are frequently covered in snow, slush, ice or some mixture of the three and in all of those cases, there’s plenty of salt. The body shape of most Subarus is such that the front wheels, even traveling straight down the road, anything and everything at the side of the car. This leaves a nasty mess of salt across most of the car, making it look filthy and harder to clean. The best part, thought, is that they also seem to prevent the formation of large ice chunks in and behind your wheel wells, which can cause serious damage if you don’t kick them off before they freeze solid (and make a serious mess on your garage floor).

‘Winter Mode’ for most means a set of snow tires and fresh wiper blades. For most of the GrimmSpeed team, it also means mud flaps. Whether you appreciate the aesthetic or not, they make an excellently functional addition to a car that sees harsh winters, gravel, mud, etc.


Knowing that I wanted to protect my 2015 WRX as well as I could, I went ahead and ordered the black urethane kit with grey logo. They arrived quickly and were packaged very well. We take a lot of care in our packaging at GrimmSpeed and it’s easy to see that the folks at Rally Armos do the same, complete with a packaged by sticker just inside the box. Each component was nicely protected by plastic, paper or both and printed instructions were included.


Installation on the floor of the shop took 30min or so. No fancy tools, no lift, no previous experience with this kit. The brackets make perfect sense and install easily and securely. I especially appreciated how there was no modification to factory parts required. The included hardware replaced a couple of the factory clips, so I just put those in the hardware bag, labeled it and tucked it into the bottom of my toolbox. The mud flaps themselves are thick and durable, contoured perfectly for the application and feature slotted mounting holes for adjustment based on preference and precise bracket location.


In closing, I should probably note that we don’t sell Rally Armor products, nor do we have any sort of vested interest in their success. We’re simply passing along what we think is a functional and inexpensive product that meets a certain need perfectly. I’m very much a DIY person myself, and 6yrs ago, I may have attempted to hack together my own kit with cutting boards or some other nonsense, but for how quick and easy these were to install and the quality of the components, this kit is an absolute no-brainer!


If you’d like to see us review other products in a similar fashion, let us know! Cheers!

The Gift of GrimmSpeed – 2015 GrimmSpeed Gift Guide

Finding a holiday gift for the car guy or girl in your life is sometimes easier said than done. If they’re anything like us, then their automotive wish list is endless and ever-changing. Here at GrimmSpeed we hope to make things a bit easier by walking you through any product-related questions you might have, with some expert advice along the way. Give The Gift of GrimmSpeed this season and don’t hesitate to call or email us so we can help you make sure your favorite Subaru enthusiast gets exactly what they want this holiday season.

Gifts under $50

  • GrimmSpeed Apparel and Swag – A t-shirt, fitted hat, keychain or pair of license plate frames would make an excellent gift or stocking stuffer for the Subaru fan in your life!
  • Exhaust Gaskets – These might not look like fun to you, but to a Subaru owner, high quality exhaust gaskets are essential, especially if they’ll be installing new exhaust components this winter!
  • Bounty Hunter Sponsorship Kit – Challenge him or her to take part in the GrimmSpeed Bounty Program. The kit includes a shirt, sticker pack and registration to compete in fun challenges to win GrimmSpeed store credit!

Gifts $50 – 100

  • License Plate Relocation Kit – This is one of our most popular gifted products! Moves your front license plate to a less prominent location and eliminates the need for holes in your bumper.
  • Alternator Cover – An excellent GrimmSpeed-branded ‘dress up’ item that typically replaces the less attractive factory cover. Available in red, black or stainless steel.
  • Electronic Boost Control Solenoid – This is another very popular gift! Although most enthusiasts already own one, if your Subaru/Mitsubishi/Mazdaspeed nut is planning on getting tuned anytime soon, it’s a must-have!

Gifts $150 – 400

  • Catless Up-Pipe – An excellent way to free up pre-turbo exhaust flow and remove the restrictive factory cat. Also available with an external wastegate option – be sure to get the correct one!
  • Air Intake System – This seems to be at the top of everybody’s list this year. An upgraded intake system reduces restriction and allows for more power to be made during tuning. It also enhances the sound of the vehicle.
  • Air Oil Separator – Another very popular gift, available in red, blue and black. Be sure to check on which fitment is needed!

Gifts $400 and up

  • Downpipe/J-Pipe – This is the starting point for an upgraded exhaust system and is the piece that generates the greatest performance gains. Available with a number of options, you may need a couple of hints on this one!
  • Top Mount Intercooler – For that very special person in your life, a GrimmSpeed Intercooler is the cream of the crop where intercoolers are concerned. Rated to high horsepower figures, it’s an excellent fit for nearly all applications.
  • GrimmSpeed Power Packages – Available with a wide range of options, GrimmSpeed Power Packages offer a fully engineered system of modifications, designed to enhance the performance of your vehicle to a number of different degrees. A PERFECT starting point for a new enthusiast.

If you have any questions about items that are on the GrimmSpeed Gift Guide or our website, please contact us directly at!

Restriction in the Stock BRZ/FR-S Intake – Introduction

grimmspeed intake testing brz frs
This photo shows placement of one of the fittings for pressure sensing.

When we began thinking about designing an intake for the twins, we first wanted to evaluate the claim that “the stock intake is good enough.” Its general knowledge that in the last ten years or so, that factory OEM intakes have become very good in design, and are often difficult to improve upon. There are several ways to evaluate this claim, and we wanted to start out with looking at the design of the entire intake as both an overall system, as well as the sum of all of it’s parts.


A visual inspection doesn’t tell an absolute truth about the system, but it does give you a place to start evaluating. The first source of restriction you’d look for is sharp or abrupt entry points. Air entering a pipe without a flared entry (think velocity stack, or a funnel shape) produces a restriction, compared to one that does have a flared entrance or transition. Just the same, when air has to traverse a larger and larger angle bend, there is an increase in restriction. The same can be said for when air has to pass over surfaces that are not smooth, etc. All of these situations add restriction, which can be measured as a drop in pressure. The ideal case to move air from point A to point B would be a perfectly smooth, straight length of pipe, and even that will have a pressure drop as the length of the pipe increases.

So from a visual standpoint, lets break apart the sections of the intake: There is a snorkel, front of airbox, air filter, rear of airbox, MAF housing, intake elbow, and throttle body. The entire system can be looked at as being the area before the snorkel (behind the bumper cover) to just passed the intake elbow (right at the throttle body). Measuring the difference in pressure between these two points will give you the overall restriction of the system. But in order to identify where the weaknesses in the system are, one would be more interested to measure the difference in pressure between components in the system. For example, to measure the restriction the air filter has on the system, you would measure the pressure before and after the filter. And if you add up the pressure differences between all parts of the system, it should equal the overall restriction.

Back to the visual inspection of the system, what do we see as a potential problem area, and why do we want to choose these locations to test? The first part of the system that air sees as it enters is the snorkel. The inlet of the snorkel looks good; there is a well formed velocity stack that has minimal extra material from being molded. It’s a slight oval shape, roughly 2.25in x2.5in. About 10 inches down the air’s path, the snorkel starts to make an approximate 90 degree bend to it’s exit. The bend is very smooth, and all the while the shape is transitioning to a flatter oval, while at the same time increasing in overall cross sectional area. At the point where the snorkel transitions into the air box, it is roughly 2in x 5.7in. The snorkel contains two resonators along the first section, in two different sizes, each containing a small drain hole at their lowest point. The snorkel is sealed to the air box with a strip of foam that interfaces the outlet of the snorkel to the inlet of the front airbox.

The front face of the airbox is angled at the bottom, and contains a circular emboss. Both features are in place to maximize area before the filter, while still clearing the radiator and fan. There is also a large resonator to the left of the entrance. The front airbox has a hole at it’s lowest point just right of the entrance, as does the large resonator, both for drainage purposes. The inside of the front of the airbox is very smooth across all surfaces. The only noteworthy point from a flow standpoint is at the entrance. The half of the entrance below the snorkel has a smooth radius flowing towards the filter. However, the half above the entrance is abrupt, and looks different than you would expect from viewing it from outside the box. Outside the box, just above the exit of the snorkel there is a hump which looks to exist as an area to smooth airflow going towards the filter, but just the opposite appears to be true as there is a void here. One can only assume this is for strength, or some phenomenon that is hard to explain.

The air then flows through the filter, which is not your typical paper filter, and has only 14 large ribs. I am unsure of the media of the filter, but it is similar to a fabric like cotton. The ribs on the front side are longer than those on the back to increase filter surface area.

After the filter is the rear of the airbox, which contains mostly smooth transitions, with a taper at the opposite side to the exit that should promote flow towards the MAF housing. The only noticeable source of restriction in this piece are several protruding ribs that run lengthwise in the rear of the airbox, however small. The exit of the airbox is technically the mass air flow, or MAF, housing. The entrance to the MAF housing appears to have been optimized, as it is one of the most important parts of the entire engine. The rear face of the airbox has a section “dug out” to smooth the transition into the MAF, and the opposite side of that feature has a molded plastic velocity stack. Immediately at the entrance is a plastic matrix that is commonly referred to as an “air straightener.” This is specifically put in place to help the MAF provide the most accurate reading as possible by modifying the flow of air before it. The thickness of the pieces of this matrix is 2mm, and the diameter of the entrance here is roughly 68.5mm. The entire MAF housing is only about 70mms long, and places the MAF sensor about 25mm, or about 1in after the air straightener. The inner diameter at the MAF sensor is 70mm, and the diameter at the outlet of the MAF housing is about 72mm. So there is a taper through the entire section, albeit minimal.

At the exit of the MAF housing is the entrance of the intake elbow. The entrance to the elbow is just under 3in in diameter, and has an immediate 90 degree bend. This bend is very tight, and has a centerline radius significantly under 3in. This most likely means that the diameter of the cross section does not stay a constant 3in as the bend progresses. There are ribs on the outside of the part for strength, but they do not exist on the internal surface of the elbow. There is a tube exiting the elbow for the sound tube, just opposite of the intake elbow’s entrance, and a resonator toward the bottom of the engine bay, both located directly on the bend. Immediately after the bend is a roughly 2.25in long flex section. This section contains 5 smooth ridges that exist on the inside of the tube, and extend outwards of the tube less than .125in. After this flex section is a 5in long straight section, smooth on the inside, with ridges on the outside. This terminates at the entrance of the throttle body.

Based on this visual assessment there isn’t much to expect in the way of restriction. From the entrance of the system to the exit, we expect to see a restriction from: 90 degree bend of the snorkel, air filter, decreased size (in comparison to the air box volume) of the MAF housing, the tight 90 degree bend on the entrance of the intake elbow, and the flex section located right after the previous bend.

See Part 2: The Equipment to Continue

GrimmSpeed Sponsors The 48hrs of Tristate Drive

grimmspeed 48hrs of tristate

GrimmSpeed is excited to announce that once again, we’re sponsoring The 48hrs of Tristate Drive in New York and New Jersey. A great deal of information, routes and registration are all available at the official website (see below). The charity this year is Alex’s Lemonade Stand, which is dedicated to fighting childhood cancer. There will be a raffle held at the Subar of America Headquarters in Cherry Hill, NJ on Friday and the more money you raise for the charity, the more tickets you get for the raffle! See details below.

  • Date: January 17-19, 2014
  • Registration & Info:
  • Cost: Drive Donation to Charity is $100, Passenger is $75

Please visit the website and contact Mike and the rest of the 48hrs committee with questions or to get involved!