If you are trying to maximize your flow and horse power I would use the aftermarket headers. Not the over the counter pieces of crap headers you can buy at any speed shop. The money you spend in this area will reflect on the Dyno. There are reasons to use short tube or a long tube lengths and various other modifications to a header tube. Spend time on researching this stuff before you buy anything. Max Wedge repro manifolds will run you about 1000+ dollars. Then you can try and buy the rest of the exhaust system.

Your choices of exhaust all depends on the motor modifications and the uses you will have the car doing. Research research research.Dont waste money with an unsuited exhaust system.