It is dirty Kenny, the same thing happened to me, but it is cool cause it doesn't bleed off the boost and when you shift you just rocket right out, but it messes up you Turbo or blower that way.
Anyways open the top where the spring is and clean off any debris that is inside I bet you that will help cause when I had 5 psi it was still loud as hell.
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DEATH MACHINE 2.0v. K-powered