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. Sizing of valve is based on flow and not boost pressure. The valve vents to atmosphere at sound pressure levels in excess of 110 db making it one of the loudest on the market. This valve requires a vehicle specific mounting flange, sold separately.