I've never heard of that. A blow-off-valve goes on the intake form the turbo to the throttle body so when you let off the gas (during shifts) and the throttle body closes, the pressure coming from the turbo doesn't hit the closed throttle body and start turning the turbo the wrong way which can lead to some pretty nasty things

I did see this one thing in a magazine though. You can buy this thing you put inside the engine compartment and it makes the swoosh sound you looking for when you hit a button. However I would say if anybody ever found you out you would be quite ridiculed to say the least lol I would say just buy a turbo and gain the horses with the sound
