The Kompact Dual Port blow-off valve directly replaces the stock bypass valve on the Subaru WRX MY08-14 and the new Nissan Juke/Pulsar Turbo. Standard valves crack with age and heat cycling and rely on rubber diaphragms that perish. They're also not designed to handle increased boost levels. Turbosmart's Kompact offers big blow-off valve performance in a small package. Its billet aluminum construction provides strength, while the precision-machined lightweight piston gives excellent valve response and sealing without relying on rubber diaphragms or O-rings. Hence, it's far more durable and guards against compressor surge even when the boost is turned up.Dual Port vents both to the atmosphere & back into the air intake. Ports with sequential timing allow quieter operation during normal driving, while getting all the benefits of a vent-to-atmosphere BOV under race conditions.