If you're talking about the header gaskets, I have them...they are like to pieces of malleable metal "sewn" together.
I have them on my car...never had an exhaust problem.
You just gotta make sure you tighten them down on a cold engine, then warm the engine up a bit, shut it off, then re-tighten them again since the heat will allow you to run 'em down further...
...or just install them on a semi warm engine. Either way, they always recommend to tighten them again after they've heated up.
Just
be careful not to burn yourself OR break your plugs off cuz that'll really make your day!!!
btw, if you're separating the headers from the heads, you might wanna wrap your headers with Thermo-tec or DEI exhaust wrap...I think it actually does reduce underhood temps (...slightly); plus they say it's supposed to push out exhaust faster and in "extreme" cases can lead to a semi-lean condition.
Good luck!!