The AVO 15psi actuator allows the factory turbo to have more solid boost response while ensuring boost is maintained at a preset level, resulting in increased torque and hp. Where the factory actuator drops boost as the revs rise, the AVO actuator delivers constant minimum 15psi boost all the way to redline and beyond. An extremely safe, reliable and effective means of raising your boost level. Fits to these stock turbochargers: VF24, VF28, VF29, VF30, VF34, VF35 & VF41 (Note to fit FV22 Turbo one Hole needs to be slotted) Applied Models: Impreza WRX STI: 2004-2007.