[Cool53]

Headers are a real science and you are never going to know if the tubes you just put on will make more power or less power, and where that power will be, unless you dyno or race the car and look at data. I have block huggers headers on my truck, which are not scientific at all, and you know how well that goes. But I did sp[end time matching gaskets and grinding the flanges to make them flow better. I also opened the collector, if you can call it that, to give a little extra room. I think that extra work makes for a better part than having a long tube set that doesn't fit.
First rule is to go with a good manufacturer. Next is to get headers with a flange that match the exhaust ports, or run transition plates. That is so critical. 99% of the cars that come in my shop have bright shiny headers with flanges that don't even come close to matching the exhaust ports.
Your exhaust system changes everything, too. Again, it might complement your headers or might negate all the good you did with your headers. Too many variables. And if you are really concerned only make one change at a time.
Equalizer tubes might work or might not work. Again, the only way to determine how good they work for you car is to test before and after. We have moved pipes all over and changed tone, and sometimes a little power, but no big gains. If we saw significant gains it is because there is something else not quite right with the system.
I love it when an engine is dyno'd with a set of rusty old tubes that the dyno guy uses and then you put the engine in your car with a different set and then expect the same results. Bring your headers along and use them for the pull. ANd make sure the timing the dyno guy is using is what you are going to use when you are ready to put it on the street. With their cooling towers they can chill the engine so much they can add as much as 8 more degrees for your dyno sheet, which is not real life at all. Especially if the dyno guy built your engine. He doesn't want to give up any bragging rights.
Headers, for the most part, as well as the rest of the exhaust, is as important as any other part of the engine build. If you can't get it out, then it isn't going to go in.