A Malpassi Adjustable Twin Piston Atmospheric Dump Valve has been designed to be an upgrade to the factory valve. Capable of dealing with higher boost pressures and is more reliably designed, meaning you can enjoy your reduced turbo lag for far longer.Uprated for higher boost pressuresReplace failure-prone factory valvesOption of atmospheric blow-off noiseWhen you come off the throttle on a turbocharged car, the built-up charge of pressurised air must go somewhere. If it can't, or if the air isn't released quickly enough then the turbo will slow down or even stall leading to a delay getting back on boost when you get back on the throttle.This is where a dump valve comes in. It releases the built-up pressure. Most cars have a dump valve of some sort fitted from the factory. This will have been tuned for the factory tune and boost levels though. In many cars, a soft flexible diaphragm is part of the valve, and these wear out. Once the valve is leaking it can cause problems with how the e