As the name suggests, a Blow Off, or Diverter Valve, is a mechanical valve that dumps boost pressure that is trapped between the throttle body and compressor wheel of the turbocharger. This pressure is created when the throttle is shut off momentarily between gear changes and deceleration. Designed and developed in the early '80's by German engineers to reduce lag on early turbocharged rally cars, this simple but very effective method has evolved into much more than just a plastic disposable diaphragm valve. The plastic type Samco diverter valves that are installed on many European performance models are prone to diaphragm failure with relatively low mileage. SamcoSport have now introduced a Blow Off Valve that are designed in the U.K. and manufactured on state of the art CNC machines. Only premium quality Aerospace 6061-T6 aluminum is used to ensure optimum performance from every valve. A range of fixed rate stainless steel springs are supplied to allow for custom boost and idling setups.The unique twin SamcoSport U-Tec Seals that are fitted inside very piston valve are manufactured from oil and heat resistant viton. The SamcoSport U-Tec Seal design gives a flexible seal to piston contact area, so this means a perfect seal even in extreme operating conditions. Commerical o-rings are NOT used. O-rings do not provide an adequate and acceptable sealing solution for high-performance applications.All internal springs and external pieces are manufactured from 316 grade stainless steel to prevent corrosion. Direct fit Installation kits for 1.8T and 2.7TT VW & Audi applications include stainless steel clamps and silicone hose rated up to 5 bar.