11.1 compression alum headed 5.8. 1 5/8 bbk swap headers. had a problem blowing out the gaskets before. The heads are getting ported right now so they should be flowing a lot more (at least what patroit claims they do out of the box). So any suggestions other than stock replacments?
i use the MR gasket header gaskets, local oreilys should carry them, i know the store in miami has them. and their only 12 bucks. dont use their paper gaskets, use the blueish colored one with the metal on the inside, these dont stick to the header and head and break into pieces when taking them off like paper gaskets.
i also found out it helps to be more delicate with them installing them. a long time ago i used to just tighten the crap out of the header bolts. so tight i stripped the threads out on iron heads. well that ruins the threads on the head plus it wont hold the header down in that areas.
make sure the header flange is flat. may be warped some but i have never had any problems with my bbk shorties. also make sure the head is clean. i also used to try and scrape old gasket off with a screw driver and call it "good enough" where there were still little bits of gasket hard to see. its worth the time to clean and prep the head surface the gasket will touch.
with my heads incar i used a wire wheel and die grinder to clean the head to super clean. havent had to clean a head of old gasket since using the good blue gaskets, they just fall off.
also when i tighten them i start from the center and alternate side side and move outward. and i dont tighten them to tight. just where they are pretty snug.
after i run the car through a few heat cycles i go back out and usually tighten them a little more, they seemed to tighten up a little more bit after running it a few times.
then for about a week or two i will periodically check and make sure none of them back out and tighten them back up if they do. and finally it gets to a point where they dont back out at all and they work great.
i dont know for sure what excatly you do but i am just sharing my expierences, i used to fight header leaks alot and it sucked.