Here is a copy of a review I sent to Myles of RCE and I thought I'd post my findings here as well. Its rather long, but complete if you may be thinking of this suspension option for your 2008-20014 STI.
Personal Review: By Thor
GTWORX/Bilstein Impreza Cup Sport Kit for STI (2008-2014)
I’ve just completed installing and testing a complete suspension system for my MY2011 Subaru WRX-STI LTD (GVB). I purchased all of the parts from GT Worx/ Race Comp Engineering and the purchase process couldn’t have been easier. The communication from Myles and Milena could not have been better. I had to wait about a month for my suspension as the Bilstein dampers were being manufactured and shipped from Germany. During this time, every email or phone call was cordially answered and addressed; that’s great customer service.
I purchased a complete suspension system to include: Bilstein Sport dampers (specifically tuned for the Subaru STI chassis), RCE #340 Super Sport springs for the GR chassis (commonly called “yellow” springs), Whiteline COM-C Strut Mounts (Group N material stiffness), rear perches and strut mounts and RCE GR Chassis front and rear hollow 25mm sway bars. To make this a quick “plug-and-play” install I requested RCE to “build” my parts for me so there was no need for spring compressors or additional parts/time on my end to complete the install. Opening the boxes upon arrival revealed one of the best packing jobs I have ever seen; each strut assembly was fully protected in its own multi-layer bubble wrap and then anchored in the larger box for additional protection. The parts were in perfect condition, fit and finish was impeccable. Full installation of the parts is very easy and straight forward, it took no more than an afternoon. That said, I do have a lift and air tools in my home garage. Both sway bars are set to full stiff and tire pressures are set to 36/34, as per RCE recommendations. After the install I confirmed with RCE appropriate alignment numbers. With a performance alignment, I am currently at -3.0 front camber (possible with the stock camber bolts due to the Whiteline COM-C mounts), 0.0 toe all four wheels. Caster is not adjustable and the thrust angle is 0.0. The ride height, which may change slightly still after additional settling, is equal all the way around and the car sits 11mm lower than stock. This is just under ½ inch and exactly what I was after. The MY2011 STI is already lower than in previous years and has much improved stock handling. The additional lowering only adds to the handling and is NOT enough to warrant or require roll center kits, etc. to keep the suspension geometry where is should be.
For background, other modifications to my car include: COBB AccessPORT stage 2.0, COBB SF Intake w/ air box w/ T-bolt clamps, COBB catted down pipe-heat taped and hi-temp coated, Perrin turbo heat shield, Agency Power exhaust, GrimmSpeed A/O separator in line with a CUSCO catch can, Perrin radiator shroud, Perrin alternator cover, GrimmSpeed M/C brace, one step colder plugs (NGK LFR7 AIX), CUSCO throttle body/intercooler hose w/ T-bolt clamps, CUSCO strut braces F/R, CUSCO front sub-frame braces, Whiteline steering rack bushings, redline full synthetic oil, Dimple magnetic drain plug. Additionally, I sent COBB Tuning several data logs for their professional review and all engine parameters are well within specified limits as recommended by COBB on the RON91 fuel map for my Stage 2 (thanks Ian). In my opinion, if you have a later model STI I’d suggest a COBB AccesPORT (or similar item of your choice) to counter the inherently lean condition these engines are sent to us in. Just say’in….
If you only want to lower your car for a certain look and performance is secondary to that look, this is not the suspension for you. If you think you need your car corner balanced and need independent compression and rebound dampening and ride-height adjustability, this is not the suspension for you. If my STI was strictly used on the track I would have purchased Ohlins R/T coilovers and I’d of been completely set for the predictable and smooth surfaces of a track and I’d be happy to adjust settings for lap times all day long. That however, is not the intended use of my STI; sure it sees track time-but less than 10 times a year. For my suspension needs I looked to the Subaru factory tuned JDM STI’s we cannot get here in the USDM. Models like the STI R206, STI tS type RA, STI 340R and even the “stock” [just springs changed] set up on the Isle of Man record setting USDM spec STI. By the way, if you haven’t seen that video, you need to. These cars are all designed for real world use and by engineers who “set cars up” for a living. I’ve tuned many of my own cars, recently an Audi S4 and my very special Audi RS6 and prior to those I’ve had several track cars so I’m not completely unaware of how cars work. I am however not a professional and I’d never assume I know more about car set up than a professional. The previously mentioned JDM STI’s all have very similar suspensions. They are still based on the standard McPherson strut design [like our OEM suspension] with various higher-end tuned dampers [KYB] and springs [STI]. In my personal opinion, this allows the cars to handle real world driving scenarios-regardless of what you may encounter; pot holes, rail road tracks, bumps, surface conditions, etc. Since that is where my car is 99% of the time, that’s where I want my car to handle.
I wanted razor sharp response, telepathic-like feedback, little pitch, roll or yaw at any time and of course a tolerable ride to drone on the freeways with. And, that is exactly what I got! My initial impression was at first a bit disconcerting, on my first drive I thought…hey, this doesn’t feel all that different from stock…substantially stiffer, but not all that different (which is a good thing). That was at a very sedate, slow speed and in a straight line. Then after driving many miles to settle the suspension a bit, I added two of my favorite things…corners and speed. This is where the GT Worx/RCE suspension comes to life. Imagine the already quite good handling of an STI honed and sharpened to a level where you know exactly what your car is doing at all times; braking, accelerating and turning. If you want the feeling in terms of vehicle dynamics, neutral and balanced would be the terms to use. Initial turn-in is crisp and immediate with the front end tracking exactly where you point it. Mid corner bumps or road imperfections are dealt with without any drama or surprises and the suspension remains active and able to handle the imperfections. There is no push (under steer) unless induced by the driver. The rear of the car simply follows the front at all times. There is the slightest hint of lift-off over steer but never an issue I had any problems with at any time. My cars “attitude” remained flat and controlled at all times, regardless of the road surface. I drove through curves with off camber rises/crests, and repeatedly one with a large mid-corner bump that would always cause the stock suspension to unsettle and push (under steer) when the front end became light after the bump. At the same speeds the GT Worx/RCE suspension still felt planted and offered plenty of feedback. Of course I was able to induce the same “push”, but it required much, much more speed. This to me evidences a suspension that remains able to maintain control of your car far beyond that of where the stock suspension fails to control the car. The GT Worx/RCE suspensions reaction to the road surface is faster, more immediate and extremely predictable in comparison to stock, or even some coilover systems I’ve driven. Pitch, roll and yaw are minimal with this suspension and now I realize the stock [USDM] STI seats are quite inadequate to deal with the performance levels this car is now capable of. Forces usually concealed by the comparatively loose, wallowing under-sprung stock suspension are now directly transferred to the driver. This is where you learn to “feel” the car and this in turn helps with car control and confidence…with confidence being the key feeling of this suspension. The suspension is firm yet compliant…quiet yet maintains stock suspension geometry and stock levels of wheel travel and does not compromise any of the user friendly stock characteristics. Having only a few short laps on a “wide open Wednesday” I don’t feel comfortable discussing this suspensions performance on a track…yet!
In summation, I am very pleased with my purchase and I have no regrets with my decision. I see on the forums there are plenty of people who need and want coilover systems but if you own an STI and would like a real world suspension with no compromises, the GT Worx/Bilstein Impreza Cup Sport Kit is worth your time to consider. Call Myles at RCE and discuss your suspension needs with him. In my personal experience, he has displayed integrity and has been open and honest with me, even advising me when a certain component (one he sells) was just a waste of money.