2004-2021 Subaru Impreza STI Black Recirculating BOV/Bypass Valve by Perrin

Adjustable relief pressure and flow control make fine-tuning on the fly simple and quick with the PERRIN BOV/BPV.

High Flow - With large 1.225" inlets and outlets, the PERRIN BPV is sized perfectly to relieve any amount of boost pressure without fear of compressor surge. Don’t be fooled by giant oversized bypass valves, these inlet and outlet sizes were chosen to ensure the perfect balance of flow and to maintain boost in your system, without ruining response by dumping too much boost.

Recirculation is Job #1 - It is vital that a blow off valve for your WRX/STI recirculates the air back to the intake track to maintain proper air-fuel ratio and driveability between shifts. While this can be set up as a vent-to-atmosphere style blow off valve, we only recommend that on cars running aftermarket Speed Density type tuning (cars without mass airflow sensor).

No Tuning Required - Increase horsepower and torque without ECU recalibration or tune! This part is designed and tested to work safely on your vehicle without any tuning required! However, more power can be gained with proper ECU tuning! Confirm any tune or recalibration you add is specific for ALL modifications added to the vehicle.

Adjustable Relief Pressure - The PERRIN BPV cap features adjustable spring tension, which allows for an adjustment when the blow-off valve vents. A looser setting will make it act smooth and more like stock. Setting it harder will cause it to vent later and with significantly increased boost levels. This adjustment is important in maintaining the air within the boost system without reducing turbo response.

Adjustable Flow Control - The unique design allows you to control the volume of air released when the blow-off valve vents. Adjusting the volume of air helps maintain the perfect amount of boost in your system during shifts without causing compressor surges. Venting too little can damage the turbo, venting too much air can make the throttle less responsive. This adjustment is independent of the relief pressure allowing for a totally customizable BPV.

Low Maintenance - The PERRIN BPV requires very little maintenance but when needed, it's very easy and quick to disassemble. Two O-rings are used to seal vital components from the elements making for extended time between service intervals. There are no special tools required and maintenance can be performed without removing the bypass valve from the vehicle.

Direct Fit and Pre-set Adjustment - Included with every PERRIN BPV are the necessary components to make this a direct bolt-on for your WRX/STI. Each bypass valve is pre-set out of the box to work perfectly with every application, so no adjustment is required.

Construction - The PERRIN BPV cap, piston & flange are all CNC machined from 6061 Billet Aluminum. The body is CNC machined from a single block of aluminum. This makes for a clean look that reduces potential failure points and leaks without additional parts.