Why is the length and diameter of exhaust systems important?
The length and diameter of exhaust system pipes is an important tuning factor. Basically the longer the pipe, the more torque you obtain. Short pipes, on the other hand, benefit horsepower. This is true for normally aspirated motors. Supercharged motors have their own idiosyncrasies that are much too complicated to cover here. Having matched lengths of pipe is important if you re trying to get optimum performance from your motor. Nearly all the pipes on the market today are designed for aesthetics with no concern as to engine performance, which is why you see different, unequal lengths, etc. It seems like the consumer thinks that if they “look pretty” and are “the louder they are,” they’ll buy them. Stepped headers (increasing the diameter of the pipe in stages over a certain length) are a good way to get maximum performance. But to get the most out of this style of exhaust requires that the lengths and diameter be matched to your motor combination, which takes time and study.
