OK, time to stir the pot a little- - - - -
I'm not convinced headers are worth the effort, unless they're a set of tuned-length pipes with exactly the same runner length from each cylinder to the collector. Also, the "tuned" length will only work right at a specific RPM range, so make sure you know where you want the horsepower or torque boost before you have the pipes bent.
My experience with headers, even with round track race engines, is DON'T USE THEM UNLESS YOU'VE GOT TO! A good set of free-flowing stock exhaust manifolds will keep the underhood temperature lower, won't leak and burn up plug wires, and generally will make your life a lot simpler! They also don't have to be re-tightened once a week, and have the gaskets changed semi-annually!
Jerry
