Actually let me make a small correction. The wastegate does not release "boost", only exhaust gasses however this has a direct effect on how much boost you get from the turbo. A little different. One is relesing exhaust gas, one is releasing pressurized air. Your WRX comes with a bypass valve stock but what you hear on the street is probably the atmospheric ones which vent to atmosphere. They don't enhance performance really on a mild car but they sound nice and in my case it was necessary (front mount intercooler). It has no negative effect on the engine at all.