Subaru Impreza WRX & STI T4 Twin Scroll Turbo Kit

Product Options
Intercooler Finish
Downpipe Coating
Turbo Options
Intercooler Options
Turbine Coating
Up-Pipe Coating
Lower Manifold Coating
TiAL Wastegates

Subaru Impreza WRX & STI T4 Twin Scroll Turbo Kit

Check out our new T4 Twin Scroll EWG EFR Turbo kit!

Full-Race engineers, following our commitment to constant improvement, took our legendary Twin Scroll Subaru WRX/STi Rotated Mount Turbo Kit and updated it for 2011. Design changes allow the Gen2 Twin Scroll to flow more, weigh less, fit multiple generation Subaru chassis and most importantly - generate the broadest possible power band with huge area under the curve. Consisting of the necessary turbocharger hot side upgrade components, and utilizing ideal cylinder pairing and the proper implementation of twin scroll technology - Full-Race engineered these kits to offer optimal performance with instant throttle response, early spool and huge top-end power - while being flexible enough to grow with your future needs and changes in driving style. Full-Race recomends using T4 frame turbochargers such as BorgWarner Airwerks, EFR, or Garrett, FP, etc. The S300SX FMW has proven to be an outstanding high power performer on the EJ25 engine. Whether you are road racing, drag racing or building a "street weapon" daily driver, the Full-Race Twin Scroll Turbo Kit is adaptable to suit any chassis and application, now including the popular 08+ STI and 05+ Legacy GT and 11+ STI.

Full-Race Subaru Impreza WRX/STI T4 Twin Scroll Turbo Kit Includes:

  • Full-Race Subaru WRX/STI Lower Manifold
  • Full-Race Subaru WRX/STI T4 Twin Scroll Up-Pipe
  • Full-Race Subaru WRX/STI T4 Twin Scroll Downpipe
  • Full-Race Subaru WRX/STI T4 Twin Scroll Kit Box

Full-Race Lower Manifold

Full-Race Twin Scroll Up-Pipe

Full-Race Twin Scroll Downpipe

Full-Race Kit Box (Fittings, Hardware, and Lines)

Optional Turbocharger

BorgWarner S200SX 75-70
BorgWarner S300SX 83-75

BorgWarner S300SX 91-79
Garrett Twin Scroll GT35R

Garrett Twin Scroll GT40R

Optional Full-Race Subaru Reverse Mount Intercooler Kit

Note: Currently only available for the 2004-2007 WRX/STI

Black Anodized

Optional TiAL MVS Wastegates

Optional TiAL Q Blow Off Valve

Optional High Temperature Coating


2011+ STI:

GR Chassis 08-10 WRX/STI, shown with BorgWarner Twin Scroll S300SX FMW Turbo:

GD Chassis 04-07 WRX/STI, shown with BorgWarner Twin Scroll EFR 7670 Internal WG Turbo

GD Chassis 04-07 WRX/STI, shown with Garrett Twin Scroll GT40R Turbo:

GD Chassis 04-07 WRX/STI, shown with Garrett Twin Scroll GT35R Turbo:


"the fact is the BW S300SX FMW is a ridiculously good turbo and absolutely unmatched for the price point. I've been trying different setups on my STI since I bought it new back in 2006... I've used a few of the FP bolt on turbos (regular green, HTA green, red), I used the ATP35R, Garrett 4088R, had a APS header up-pipe (four of them actually because they kept cracking), a Full-Race 1.5 scroll kit, and a Full-Race complete TS kit (what's on the car now)... The BW S300SX FMW, by far has out performed any of my previous setups... I have spent a lot of time and money trying to make this car a respectable fast daily driver, and had all but given up before Geoff told me about this new BW turbo...This turbo just flat out kicks butt - good boost threshold, makes great power all they way up to my 8000rpms rev limiter, and the boost recover between shifts is just flat out instantaneous... I'm pretty confident that with E85, this turbo will do over 650whp with even more gains in the mid-range - I admittedly was surprise to see the boost threshold of a 35r and the power of a much larger turbo... On the dyno, we were hitting peak boost of ~29psi and then it would taper to ~27psi at redline, on the street it holds 30psi across the board." Phil Petraca

The following graph compares Phil Petraca's 2007 Subaru and Full-Race Twin Scroll Turbo Kit equipped with BorgWarner S300SX FMW VS Garrett GT4088R

Application Notes:

  • The OEM Subaru triple layer steel gasket is strongly recommended. There are other less expensive options available, but this is the best because it has a built-in crush ring and is steel so it will not deteriorate. The Subaru part number for the exhaust gaskets is PN # 14038 AA 000. Torque properly to factory specifications.
  • Fits OEM oil pan only.
  • Some chassis may require a small bend to the aluminum A/C line at firewall (most do not).
  • Wrap wire loom as it comes out of firewall with heat wrap and pull with zip ties towards shock tower for additional clearance.
  • 2000 degree ceramic coated turbine housing is STRONGLY recommended.
  • 2000 degree ceramic coated up pipe, downpipe and lower manifold also recommended.
  • Heat wrap recommended and will not void warranty.

Full-Race Rotated STI kits require PS hose modifications. *If you dont want to modify the powersteering hose please look at our Subaru Stock location EFR turbo kits

Full-Race 08+ STI kits requires heat protection around a safely secured ECU plug and the installer should relocate the ABS mechanism higher on the strut tower. This allows the 4" intake tube to fit through. Pics of stock ABS location (and bracket) interfering with 4" inlet:


Subaru Impreza Sti MY12, 2.5 engine, complete Full Race T4 turbokit with intercooler and BW 8375, 1000cc injector, at 21psi on 98oct fuel:

For more information and or related questions, feel free to contact us.

  • (866) FULLRACE