This superb DPR blow off valve features the SSQV twin piston design – small piston for low boost shifts, both pistons for higher boost shifts. These units are leak-proof due to a pull not a push design – the more boost you run the better it seals. This particular design features plumb back adaptor, perfect fro vehicles with air flow meters that oftenn suffer when atmospheric venting valves are installed such as wrx, sti, evo, gsr etc etc. Can also be run in atmospheric venting mode, providing you with the ultimate BOV flexibility! Available with a range of flanges, get that great unique sound!