The Tubi Style Audi V10 Muffler valved exhaust system produces an aggressive note under acceleration, but a more civil tone during stop and go driving. It does so by the use of of vacuum-actuated flaps that open and close depending on the driving conditions and input from the driver. When open, the valves allow gasses to escape through a second outlet from the muffler which facilitates a much larger volume of exhaust to freely pass through the muffler. This not only provides a much more aggressive sound, but also contributes to a noticeable increase in overall performance.