The Active Autowerke Blow Off Valve provides greater capacity for high boost 135, 335, and 535i's with the N54 twin turbo motor. Active Autowerke's single blow off valve sports a huge venturi, designed to handle excess pressure build-up against the turbo compressor impeller blades. That pressure can cause the impeller to stop spinning (a.k.a. Compressor Surge),which can damage the compressor wheel and shaft. With the Active Autowerke Blow Off Valve in place, the stock turbos are protected as the boost is raised – you can take HP to the stratosphere, enjoy the spoils of all that performance, and get that cool “whoosh” sound as your machine spits out excess inlet pressure. All hardware & fittings on the Active Autowerke BMW Blow Off Valve have that quality factory look you demand, and are built to perform flawlessly under the most aggressive boost conditions. Active Autowerke BMW Blow Off Valve Key Features