Inefficient factory blow off valves (BOV) can hinder boost response during shifts and can limit the amount of boost pressure that can be built by your turbocharger. PERRIN offers a BOV that can handle practically any amount of boost your turbo can create! For clients that demand idle quality, and the best in drivability Perrin offers a fully recirculated BOV. Like the stock valve, the PERRIN recirculating valve keeps the vented air in the intake system to keep the ECU running smoothly. BOV's that vent to atmosphere can run rich between shifts causing backfires, cause idle issues, and effect drivability on cars that have MAF sensors. This is due to metered air the ECU thinks is being ingested by the engine actually being expelled to the atmosphere.
With the PERRIN valve, there is no reason to add more washers or change the spring to allow it to hold more boost. This BOV works very differently than others in that there is no need to have a spring to hold boost! The boost pressure is put on the back of the piston to keep it closed,and helps keep the piston from lifting prematurely. This allows the BOV to hold more than an almost unlimited amount of boost!
This will not fit the Forester unless a PERRIN Top Mounted Intercooler is fitted at the same time.
