Whatever happened to the idea of cutting the header flanges to make 3 individual pieces? A lot of time that thick flange doesn't give and if something is slightly off, make sealing the headers a pain in the rear. If you cut the extra metal between the cylinders, except the two in the middle (for non hemis), you now have "floating" flanges and have some flexibility to them. Not to mention it may give you some more room for your spark plugs. You can even cut the gaskets down or leave them as one piece for easier installation.