Aeroflow 11 Psi Blow Off Valvespring Use With 64-4050 New

these replacement blow of valve springs are specificallydesigned to fit inside the Aeroflow performance 50mm blowoff valves. Both of our Aeroflow performance blow off valves feature a 11psi spring from out of the box. If you wish to change this spring, weoffer either a softer 6 psi for turbo setups or a 2 psi spring designed for supercharger options.