[jmatta]

My personal opinion, for a street car, is you are wasting money to gain negligible HP, if any (you may lose low end torque). You will open the door to a constant CEL and will not pass emission testing, on top of it. Is all that trouble worth it?

If you really want headers, bite the bullet and get a decent pair with hi-flow cats like the ones Fabspeed markets.

I have stock exhaust manifolds, cat bypass pipes and a sport muffler on my Box S; sound is terrific and emissions legal.