i got slp headers and used the old (napa) F7139 donut seal on the tube flanges. they worked pretty good, needless to say, but now that i'm ready to put the headers back on, i've yet to be able to get whats left of the donut seal out of the flange on the exhaust side - header side separated cleanly. obviously not a whole lotta room to work, either, but never seen anything like this before. i'm starting to re-think using that same type of seal again, cuz this hassle sure ain't worth it... anyhow, they are "mashed" in there pretty good and coming apart in flakes only, at best.

 

Dremel that **** out of there. If at first you don't succeed, apply brute strength.