The exhaust gas in the exhaust pipe will form a small back

pressure, if the back pressure is too large exhaust can not proceed smoothly, indirectly leading to the engine piston needs to consume more energy to launch, increase the power consumption of the engine, and even affect combustion,

so in order to timely reduce the back pressure of the exhaust system, Make the exhaust more smooth, let the car "into more, exhaust faster", the design of the exhaust port is very important, which is why there will be double or even four exhaust ports.