I have a Blitz BOV with the spring loose enough to open during VAC and shut at open throttle (no boost). When I'm boosting and change gears, it sounds like something's reverbing out of the turbo itself... I know air is coming out of the BOV because I can feel it when I close the throttle plate after revving. Shouldn't it make a loud noise with no reverb?

 

As long as its not compressor surge its ok. Compressor surge is kind of a fluttering chirp. Sounds really cool though, but its not good on the turbo.

 

That's what it sounds like... Fluttering from the turbo... It's almost like the BOV isn't evacuating enough air... It's supposedly made for an SR20