i am debating wether or not to get a full cat back system or to just go the cheaper way and have a shop put 2.25 inch piping in there from the cat back but then it wouldnt be mandrel bent, will this hurt performance at all? will i see any gains from enlarging the piping? i have read all the exhaust articles and its still not clicking, what all would i need to make a great exhaust system, headers, downpipe, cat, cat back, muffler? is this correct? if so would it be the best to buy a cat back first or headers or what u konw what im sayin. thanks in advance.