Perrin Red Bypass Valve 2015-2021 WRX

Add horsepower, quicker response, and reliability with the PERRIN BOV/BPV. A must-have replacement for the leaky, slow responding, and plastic OEM blow off valve. 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 to the vehicle.  ESSENTIAL FOR PROPER PERFORMANCE During testing, it was determined that until approximately 3 psi of boost is reached, the OEM blow off valve does not seal. This leads to a loss in horsepower and slower response from your turbo. The PERRIN BPV solves this problem with a proper seal as well as being fully adjustable. This means faster response times, consistent boost, and overall better drivability. HIGH FLOW The tiny outlet on the OEM BPV restricts the rate at which boost can be vented. Cars running higher boost levels and larger turbos can experience compressor surge, damaging your turbo. The PERRIN BPV has a much larger outlet and is fully adjustable, eliminating this concern.  With large 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 blow-off valves, these inlets 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.  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 smoothly 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 response. This adjustment is independent of the relief pressure allowing for a totally customizable bypass valve.     RECIRCULATION IS JOB #1 It is vital that a bypass valve for your WRX recirculates the air back to the intake track to maintain proper air-fuel ratio and drivability between shifts. While this can be setup as a vent-to-atmosphere blow-off valve, we only recommend that on cars running aftermarket Speed Density type tuning (cars without MAF sensors). 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 blow-off valve from the vehicle.  DIRECT FIT& PRE-SET ADJUSTMENT Included with every PERRIN BPV are the necessary components to make this a direct bolt-on for your WRX. 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.  FINISH The PERRIN BPV body comes with a red anodized finish and the cap is black anodized. The anodizing keeps the bypass valve looking great during its lifespan. The bypass valve body and cap are laser engraved in vibrant lettering to make it easier to read.