Originally Posted by xsperf
this may be a stupid question, i have really never been that knowledgeable about turbos, but is a blow off valve like a replacement for a wastegate? is that why on cars that are stock turbos(such as audi's 2.0T engine) do not have a whistle when the throttle is released?
A blowoff valve is completely different than a wastegate.
A wastegate is used on the exhaust side and regulates the speed of the turbo by bypassing exhaust gasses.
A blowoff valve is used on the intake side and releases excessive boost pressure when the throttle plate is suddenly closed.