Flow Masters are chamber style mufflers and should not be used in a turbo application. The chamber design is restrictive and more of a amplifier rather than a muffler. The biggest reason it sounds so bad is because the system was built without a balance tube to balance both sides of the engine. The raspy, fluttery sound is caused from the two sides being completely separate. Without a X or H design in the system you hear the two separate pluses and it also hurts the mid RPM performance.