About the intake and exhaust system modification, exhaust system modification is more popular, because the exhaust system, especially its tail section, it is not only exposed on the outside of the vehicle and visible clearly, but also can be issued breathtaking audio and sound. Due to the cost considerations, noise pollution and different emission standards limitations, the original exhaust system designed will be very conservative. Then in some extent, the exhaust efficiency is not high and it will limit the engine performance. So exhaust system modification can bring the owners some unexpected gains.