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Published on Dec 15, 2008
The butterfly valves bypass the muffler and make the car a lot louder; they are being actuated by engine vacuum and thus only open after about 1 inch of throttle travel; the car is quiet when cruising, but loud when I'm on the gas: best of both worlds! Vehicle is a 2006 Corvette Z-51 with a Vortech V2 Si-Trim SQ Supercharger running 10PSI boost.