The new Blowoff Valve DD ( Dual Drive) design flows 20% more than our previous model while emitting a uniquely aggressive sound. For maximum response the DD uses the small port for low boost and a a larger port for high boost. The user has the option of using a mini SUS power air cleaner or the open atmosphere design. The blow off valve is constructed of heavy-duty die-cast aluminum and is capable of handling up to 18psi(1.2bar).