EPMAN Bolt-On Top Mount Turbo BOV Blow Off Valve For Subaru WRX STI 02-07 EJ20/EJ25 (Blue) Perfect for almost ANY turbo application. CNC machined high quality anodized aluminum construction is lightweight and durable. Provides a loud blow-off sound when boost is released. Advanced spring design allows for great response and performanceat high boost Large valve for increased airflow