i think i have the same problem... i dont think my BOV is actually opening when i let off the throttle... cuz it makes loud noises, and it is a bad thing cuz it creates increased thrust loading on the compressor wheel when the throttle snaps shut... its compressor surge... its bad during prolonged periods. but it wont kill the turbo if you use it for a few test drives... just dont let it go on for long.

and i dont wanna hear how the GN's and the T-types dont have BOV's and do just fine w/o them..