[nissanfanatic]

The science behind exhaust is backpressure, sound, and restriction which can cause backpressure. Tubing diameter is porportional to backpressure. Backpressure is good for torque but bad for high rpm power. It all depends on what the flow rate is for your engine and where you want to make power. All the technology in exhausts is based on trial and error. The straightest possible system is best because turns make restriction. This is where mandrel bending comes in. Sound suppression is basically either straight through mufflers or baffles. Apexi, greddy, and HKS just to name a few are all straight throughs. Flowmaster is an example of a baffle system. A series of walls inside the muffler make the sound waves collide and cancel out, but there is no restriction. Just a little lesson for you. You decide, but if I were to buy an exhaust all over again, I would have a shop do it and pick a muffler.