GSC Power-Division billet S2 camshafts for the USDM STi and WRX with Intake only AVCS. These cams are built to suit the high horsepower Subis. With a power range of 500 WHP and up, you need some certain mods to utilize the true potential of the S2s: built motor, with a built/ported head, and a turbo capable of supporting 500+ WHP. Upgraded valve springs are required; beehive valve springs are recommended, but not required.