GReddy Blow Off Valves are easily adjustable to eliminate compressor surge and preventing premature boost leakage, while increasing boost response between shifts. Each valve 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 the three different sizes give the GReddy user the option to match vehicles with mild upgrades to heavily tuned engines. Flow is increased with a large 40mm valve, while response and pressure is improved with optimal “diaphragm to volume ratios”  and carefully selected dual spring rates.  Another breakthrough is the unique 8 discharge ports in the CNC machined aluminum discharge funnel draws surrounding air to amplify the blow-off sound, however this can be replaced with optional re-circulation adapters in various sizes.  The Type-RZ is compatible with standard GReddy Blow-off Valve flanges. It's ideal for the 100-400hp range.