I have put on a Pacesetter header, a Flowmaster high flow catalitic converter and a MBRP Cat back system. You might have to buy a small peice of exhaust pipe between the cat and exhaust as the after market high flow I bought was shorter then stock. Also I had to cut the oxygen sensor holder from old cat and weld back into new cat (could not find a one new). Just the header before the rest gave my 2.5 a boost in power. The rest has made it able to climb steeper hills at highway speed easier. I also have a cone filter on the front of the black box above the throttle body.