RawBurt
Hard-core CEG'er
Your probably making less boost now, as theres less restriction. The spring in there maybe rated for higher causing it to flutter. You can throw another washer in to see what happends. Blip your throttle to see if the valve moves, if it does than it needs that shim. Its possible it could be leaking around the o-ring or the base. RFLS are crap BOV's any way. Ditch the leak pos and get something better.
I agree with this. When I turned the boost up on my old SVT, I had an issue where the bov was not operating properly. It wasn't blowing off, and giving off more of a fluttering noise, I'm not sure if it was the same noise you are getting ryan, but it sounds like it. I solved the problem by shimming the bov accordingly.