On the header thing, please read:
http://www.exhausting101.com/ and:
http://www.speedtalk.com/forum/viewtopic.php?f=1&t=41836 and:
http://www.speedtalk.com/forum/viewtopic.php?f=1&t=36702A couple of things about header design:
1) most are too big with too restrictive of bends
2) The header tube does not need to be any larger AREA wise (and often smaller) than the exhaust port it's attached to, at least to start out with. The primary should start with the same AREA as the exhaust port and then step from there depending on power/rpm/etc
3) 4-2-1's will allow a broader powerband with no loss of peak (when designed correctly) and are easier to package and offer more ground clearance.
4) Primary length is about #7 on the list of importance in header design. As long as it's in the ballpark it's close enough, the reason for this is that unless you have a 500 rpm powerband, one pipe "tuning" at 100 rpm less than another really doesn't matter.
5) the most important part of the header is the port-match and the bend radius off of the cylinder head.
6) When the area increases the exhaust releases energy as it slows down, this can be seen as heat. This is why collectors and tight bends are always the hot spots, you are giving up exhaust energy. Once it's gone you can't ever get it back either. This is why header for header stainless steel will make more power. It 1) keeps it hotter and 2) doesn't rust so the inside stays smoother.
7) Anti-reversion steps/valves work very well but most put them at the wrong spot. The cylinder head is the wrong spot, the end of the system is the correct spot
No header is going to get the op the power he wants. #1, the lobe separation is too wide, especially considering the compression. #2, th duration is fine, I just built a 464 inch Buick with 230/236 duration and it peaks at 5900-6000 rpm @ 598 hp. It has heads that are done nicely (hint hint). #3) if you need to run that wide of LSA because of your efi system, you need a different efi system. There is power to be had in electronics too, proper injector size (much bigger than you'd think) injector timing, throttle body size, etc, etc, etc.