Have you guys ever tried Byson gaskets?
www.byson.com
These guys make great gaskets made from industrial asbestos impregnated polymer. Most of the big companies won't use asbestos because of all the hype about cancer caused from asbestos dust. There's no dust here. They are thick, soft, tolerate extreme temperatures, and I've never seen one leak...even on warped flanges.
My daily driver (F150 Lightning) has warped motorsport headers. Felpro's leak. Coppers leak. The soft aluminum gaskets leak. I put a set of bysons on it, no leaks. And, as I said..the flanges are visibly warped. Probably .040" end to middle. The byson gaskets actually melt around the inner area of the port, creating a seal. When you remove a set, the inner material is shiny black and wicks/fills the crevises in the area. Pretty damn neat material.
Byron Reynolds
RACE Systems
San Jose, CA
http://www.racesystems.com