For some reason my turbos make a spool up spool down squeek. Its very faint, but if you listen for it you can hear it. No smoke though. Boosts just fine and pulls like none other. There's only one issue. The turbos are nice and quiet (except for that spool up squeek) until I get to around 5-7lbs of boost. Then the tone changes completely to a more roar noise. It sounds like a leaky bov, but Ive swapped it with 2 other working ones and it doesnt change. I dunno what could be causing it. Any suggestions?

 

I don't believe that your blow off valve will make any noise when you are boosting. Most likely something else.

 

Do you get to 10psi (or full boost)? If not, it's almost certainly a boost leak.

Dave