Designed for high performance, Blow Off Valve - Type H relieves compressor pressure surge caused by changing gears or backing off the throttle quickly. This valve is an extremely important part of any turbo system allowing quicker turbo spool up between gear changes and greatly increasing the life of a turbocharger. • The BOV Type H provides greater venting flow than the Type S and is designed for turbo charged engines running 10 to 25 psi boost. Each valve is individually tested to hold 30 lbs. of boost