Here is always the question: What are you going to do with the car? Are you trying to be serious at the drag strip, are you going to drive it on the street 99% of the time? The lower the rpms, the smaller the difference between the two. If you are actually going to drive this on the street, after you bottom out the headers where they hang out from under the car and smash them to half their original size, I bet the manifolds with undamaged pipes will beat them. It's fun to compare things on a dyno including a new set of pristine headers, or if the car is just going to roll off the trailer and onto the drag strip and never see road miles, that's one thing, but that isn't where many of us actually enjoy our cars. Many headers have to be beaten on and compromised just to get them in the car.
