The Subaru Impreza WRX STI (formerly STi, officially changed in 2006) is the highest standard-edition trim in Subaru Impreza line.
In the late 1980′s, Subaru created the Subaru Tecnica International (STI) division to coordinate development for the FIA World Rally Championship and other motorsports activities. After the company had grown, the division was used to create high-performance consumer versions of the Subaru Impreza WRX, an AWD car with a turbocharged flat-4 engine, leading to the development of the Impreza WRX STi. Subaru has used a race-prepared version of the WRX STI as its rally platform since the model trim’s creation.
In 2001, Impreza line received complete update. The chassis was stiffened so that it had 120% torsional stiffness increase. The WRX STi gained 17″ x 7.5″ alloy wheels over the previous 16″ x 7″ wheels. The 5 speed transmission (reputed to be one of the car’s weakpoints) was changed to an STi engineered 6 speed manual transmission. The engine was retained from the Version 6 STi and still retains the semi-closed deck block and is still labeled as the EJ207. However, the turbochargers are IHI models. The interior was updated with a STi logo on the gauge. The STi’s gauge also has a red shift light. The STi’s and optioned Type RA STi have received Brembo 4 pot front and 2 pot rear brakes while the bare-bones Type RA STi still carried the Subaru 4 pot front and 2 pot rear brakes. Externally, the STis had larger hoodscoops and had foglight covers with STi embossed on them. The DCCD was updated so it can work with anti-lock brakes. During braking, when the ABS is on, the DCCD will set itself to open-mode (no locking).