[Lawrence Coppari]

Also check the blow off valve to see if it is letting off pressure. I doubt the air filter is the problem. It's a hose or the blow off valve. There are a number of small vacuum/positive pressure lines in the system. If they are leaking (at the y's), your blow off valve will not remain shut. Blow off valve also has a diaphragm in it. Check to see if diaphram is torn. Nipple on top should be a dead end. If it does not hold + pressure, diaphragm is torn. Positive boost pressure holds blow off valve closed in addition to spring force.