suggestion on new exhaust

a header, is basically your exhaust manifold(fancy term). you benefit from a header. also: ALL OF YOU GUYS WITH 4BANGERS, NEED TO STOP CALLING YOUR HEADER, HEADERS. YOU ONLY HAVE ONE!!! headers come in different types ceramic. or stain-less steel. 4-2-1 or 4-1. there are so many brands available. most popular: DC Sports, greddy, kamikaze(i have these, they have the best dyno #'s fora supercharged engine), airmass, neuspeed.
a cat back exhaust system is basically a exhaust system that starts from your cat. piping, resonator(if there is one), muffler, tip.
if you already have a peformance muffler and tip, just get a header, hi-flo cat, and mandrel bent piping if a muffler shop can do it, if not go ahead and get about a 2.25-2.5 in. piping. if you still have a resonator on your piping, you might want to have that removed. when i first did my exhaust sytem, it consisted of a greddy header, carsound cat, 2.5 in piping with no resonator, and a 5zigen border exhaust. that combo was loud as a mofo. when people say restriction, they mean back pressure. if you are going NA or only have few bolt-ons, you need some back pressure. turbo or any FI cars are better with little or now backpressure.