Ok, forgive me, for I am mechanically challened, but when speaking of a "cat-back" system, I am getting that that is the pipe directly behind the converter, through the muffler, then out to the end of the tailpipe. Now, my question is what is the benifit, performance-wise, of having a cat-back system over just replacing the muffler to a free-er flowing muffler? Isn't the only difference the piece of pipe in FRONT of the muffler going backwards to the cat. conv.?