The redesigned Type H-RFL is for high performance applications with the desire to be noticed! If you need to ask this valve is too loud for you! A new larger billet aluminum body and a beefier piston ensures the valve remains smooth under the most demanding circumstances. This valve relieves compressor pressure surge caused by changing gears or backing off the throttle quickly and is designed for turbo charged engines running up to 25 psi boost. The Type H-RFL Kit includes : TurboXS Blow Off Valve Type H-RFL Mild Steel Zinc Plated Weld-on Adaptor Aluminum Weld-on Adaptor Spring Adjusting Packer Washers For custom turbo applications, the TurboXS Blow Off Valve Type H is installed directly into the connecting pipe running between the turbo and the throttle body housing. MUST PURCHASE WRX, EVO, or SRT-4 ADAPTOR KIT TO INSTALL BOV WITHOUT MODIFICATION!!!!