Loud exhaust does not mean powerful horsepower. In the rally field, we often hear very sharp and loud exhaust sounds. In fact, the way of these racing cars is to change the exhaust system into the straight-line type, that is, to choose the common drum C-03# or remove the middle tail silencer responsible for silencing, so as to reduce the weight of racing cars and ensure that the racing engines have good dynamic performance at high speed. If the exhaust system is changed to direct exhaust, it will not only solve the problem that the back pressure affects the smooth exhaust, but also cause excessive noise and affect people's normal life.