I recently installed a Greddy RS bov. Whenever I'm driving with it, if i let off the gas, but don't disengage the clutch, it makes a very sad whistling sound. It starts high in pitch and goes down then goes away. I'm assuming it's that the bov isn't adjusted correctly. I noticed that if I tighten the adjuster, it does it less, but I've been reading about a lot of people saying they have to have the adjuster almost all the way out. Am I reading whats going on correctly? Thank you very much.

 

Assuming you have a boost gauge, what is your manifold pressure when you let off the gas?

 

This only happens in vacuum, usually around 5-10 inHg. If I hit positive boost, it account s like normal.