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2004 Subaru Impreza WRX STI - Remix Baby!

Sometimes Simple Is Better As Is The Case With Jsc Speed's STI

Chris Candido
Jul 1, 2009
Photographer: Courtesy Of JSC Speed
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Tuners are often praised for being unique, custom-fabricating and building one-off vehicles. While being different can be a good thing, sometimes sticking with what works is simply a better idea. Being a car guy doesn't always necessitate custom-fabbing every single part. Take JSC Speed's project STI for example. Their Sube utilizes a calculated collection of off-the-shelf parts and a stock ECU reflash to make a ton of usable power while still retaining drivability. With the prices on older STIs dropping off as time goes by, they can be picked up for a bargain, even as the MSRP on the new models keeps rising.

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JSC purchased this '04 STI at a local dealership for a good price but it was also modified, including parts like a Hydra stand-alone ECU, Power Enterprise 850cc injectors, an 18G turbo and external wastegate setup featuring a TiAL 38mm unit, exhaust, 3" downpipe, Volk rims, and Defi gauges - not bad for a used buy. Unfortunately, it also had its fair share of problems including various exhaust leaks, a blown turbo and a cracked ring land leading to 40psi in cylinder #4. Surprisingly, even with these issues, it drove fine as a daily driver (as long as you don't mind the smoke). Since they knew plans would eventually lead to replacing the engine internals, JSC saddled up the horse most people would have shot behind the barn and got to work.

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A plan was devised to do a budget rebuild on the engine, repair the turbocharger, re-weld all of the exhaust piping, and retune the Hydra ECU. The engine was removed, disassembled and sent to R/T Tuning in Landsdale, PA for machining, balancing and a rebuild. JSC chose OEM bearings, CP Pistons and Eagle rods for a solid yet affordable bottom-end. The heads were sent to Slowboy Racing in Indiana, PA for a 5-angle porting and polish, and re-assembly using the stock cams and valvetrain. A few weeks later, the heads and block were reunited, and bolted back together with ARP head studs and Cometic gaskets. With a built motor ready to be reinstalled, they decided to change direction and install a bigger GT35R turbo from Perrin Performance. In stock form, the STI has limited space for a large turbo because the inlet is routed under the intake manifold. The Perrin rotated kit remedies this by turning the turbo 45 degrees and going around the manifold; this allows for large 3" inlet turbos like the GT35R to fit in the STI's engine bay in Garret's native 3" housing for optimal flow. Combined with Perrin's front-mount intercooler and blow-through boost tube, the turbo kit replaces all of the intake piping and the bulk of the exhaust piping, transforming the STI into a monster for just under $5K.

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A modified car is nothing more than a collection of parts without a good tune. Knowing this, JSC traveled 150 miles north to New York to visit Automaster in Westchester. Automaster's Rob Bonamici has built and tuned many big-powered Subarus, including a record-setting 630whp stock-ECU STI. After tuning, the STI peaked at an impressive 450 wheel horsepower on Automaster's dyno. But the Hydra, an early unit that came with the car, started acting up shortly after, however, and was eventually replaced with a stock ECU, which Bonamici tuned to an impressive 500 whp; incredible numbers when you consider that a stock STIs pushes about 210whp on the same dyno.

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Outside of performance, JSC chose modifications that add to the subtlety of the vehicle. Suspension modifications are limited to JDM STI springs and a Carbing front strut bar. They also installed a set of 18" Enkei RPF1 wheels for the lightweight and good looks. A Seibon carbon-fiber scoop-less Impreza RS hood and wingless trunk-lid add some subtlety to the STI. The effect is a car that struggles on the line between tame street car and ferocious street monster; an exaggeration of the STI's factory purpose. Best yet, it still feels like a stock car: a really fast stock car. How fast? It has only made two passes down the 1320 to date with a best time of 11.6 at 123mph on street tires. With launch control and a better 60-foot time, they're pretty sure they can whittle this number down to a low 11 or a high 10.

JSC Speed's project exemplifies the capability of Subaru's STI and its astounding abundance of aftermarket support. For less than $30,000, a used STI can run the quarter mile faster than a GT-R, make 200 more horsepower than a stock 2008 STI for $10k less, while still being daily driven. The car demonstrates what can be done with off-the-shelf parts, a built engine, and a solid tune. The fact that an STI can be taken this far without becoming a pain to drive speaks volumes to Subaru's original design. Combining the abundant aftermarket, massive online knowledge base and forums, and capability of the STI as a platform, JSC Speed succeeded in building a reliable monster of a car that looks and performs on a budget. Looking for the same thing? Follow the formula, buy an STI, get the same parts, and get a solid tune. It is that simple.

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Fast Facts
2004 Subaru STI
Owner JSC Speed
Hometown montgomeryville, PA
Daily Grind retail parts sales

Under The Hood Perrin GT35R turbo kit; custom 4-inch intake; Perrin Signature Series front mount intercooler, crank pulley and Blow-Thru Boost Tube; Borla XR-1 Exhaust; Power Enterprise 850cc injectors; Walbro fuel pump; HKS SSQV blow-off valve; AEM methanol injection; CP pistons; Eagle rods; ARP head studs; balanced rotating assembly and polished crank; polished head with 5-angle valve job and ported tumblers

Drivetrain Fidanza flywheel and clutch

Brains Hallman Pro EX boost controller

Stiff Stuff Whiteline anti-lift kit and steering bushings; Carbing front strut bar; JDM STI pink springs; Group N top hats; Kartboy short shifter and bushings

Rollers 18-inch Enkei RPF1 wheels

Stoppers Goodridge stainless brake lines

Outside rolled fenders; V-Limited front lip

Inside Defi boost/EGT/oil press/Link Unit gauges and warning light; ATI triple gauge pod; AEM wideband UEGO

www,,,,,,,,, (Carbing/Defi),

By Chris Candido
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