Rev. G (2007)
The WRX STI and STI Spec C is mechanically similar to the previous revision.

Changes include a different turbocharger VF43 equipped with a slightly larger wastegate port to prevent boost creep (VF43, as opposed to VF39 in the older version) and revised gearing on the 6 speed manual transmission. They also use top feed injectors instead of side feed injectors like the previous STi models(04-06USDM). This means the intake manifold is a bit different as well as the TVG (Tumble Valve Generators) used for emissions on cold start-ups. Subaru also significantly reduced the size of the restrictor pill in the boost control system.