Greddy Type-RS Blow Off Valve Kit - Toyota Supra Turbo 93-97. GReddy Blow off Valves are easily adjustable to prevent both premature boost leakage and compressor surge. Each Greddy RS BOV and Type-S is made of durable cast and billet aluminum frame and the valve to diaphragm ratio provides performance that cheap piston types cannot offer. The spring stiffness adjustment screw and 3 different sizes give the GReddy RS blow off valve user the option to match vehicles with mild upgrades to heavily tuned engines. Also available in an easy to install Greddy type-RS BOV kits form for many turbocharged vehicles.