Rev. F (2005)
The WRX STi receives the same increase in wheelbase as the Spec C. All STis received additional rear fender flaring in order to allow an increase in wheel size. The wheel size went from 17″ x 7.5″ to 17″ x 8″. In accordance with the increased wheel width, steering lock-to-lock turns have been reduced. Wheel hub strength was improved. The P.C.D. was changed from 5 x 100 mm to 5 x 114.3 mm. The interior was vastly improved as well. A whole new center console now brings out a very high grade interior feel.

The WRX STI continues on relatively the same. The Impreza line’s looks have been updated.

The WRX STI Spec C’s receives the Arai tuned dampers and a 21 mm (0.8 in) swaybar. The rear suspension is changed from rubber bushings to pillowball bushings. The strut tower was further stiffened for improved handling and stability. The strut towers were reinforced for better handling and better ride characteristics. The engine mounts were changed from metal to liquid-filled plastic mounts to reduce vibrations into the car’s cabin. Some 2006 owners have had issues with these plastic engine mounts. The manufacturer will replace them, under warranty if broken, with the 2005 rubber mounts.

The DCCD is updated with the use of a torque-sensing mechanism inside the DCCD. The torque split is changed to 41/59.

The WRX STI Spec C was used for Group N homologation.

The WRX STI Spec C Type RA was released in November 2005, with 350 units produced. The Type RA added the following to the Spec C model from the STI parts catalogue: 4-way STI adjustable inverted struts, STI Japan-spec pink springs, STI rear lateral links, STI rear trailing links, STI 21 mm (0.8 in) rear sway bar, STI rear pillowball suspension, STI 110 mm (4.3 in) opening rear axleback exhaust, STI 17″ x 8″ Enkei-made wheels and STI V-lip front spoiler.