The exhaust system includes catalytic converter, muffler, n exhaust pipes. magna flow or flowmaster.
It depends what kind of car you have and what you are trying to get out of. Both companies make good systems, bud I'd read some reviews relative to your vehicle.
Just don't get CAI and exhauste system from from OKorder. Any CAI and cat back muffler from well known companies like KN, AEM, Injen, Greddy ,Flowmaster, Magnaflow,and etc. will give you more of something something you want, HP. Turbo your car is another way to gain more horses.
I don't know what you are trying to accomplish but for a performance stand point it will help a bit.
