Is a blow-off valve required for a turbo setup with mid to high boost? Would a bypass valve still work without any or little loss of power? I'm just wondering because I may want to put a turbo in probably next summer. Though I love the sound a BOV makes, I don't want to make it apparent to others that I'll have a strong turbo.

 

A BOV is used to prevent compressor surge... that is once you're in boost, and you let off the throttle, the "built up boost" isn't stuck in your charge pipes and forced back into your turbo. It is "blown off." This prevents stress on your turbo because instead of putting force on the fins in the OPPOSITE direction to which they are spinning, the pressure is released. This not only reduces stress on the turbo but would also help with spool up times since the fins don't have to battle built up pressure after a gear shift.

One way to reduce or get rid of the BOV sound is to be light on the throttle. Instead of just letting go of gas when you're shifting, ease out of the throttle. I do it all the time. I also like to keep my car quiet. Hell I have my IC painted black so you can't notice it.

 

That being said...you don't have to have a BOV that makes a ton of noise to impress your friends. There are very simple and effective setups made of plastic by companies like Bosch (and cheap)...or, you could get one with a horn the size of an airhorn made by turbonetics and grin while you drive your car off throttle.