I had the same concerns and called FM and talked to Jamie. He said to use the stock gaskets and suggested there should be no need to replace or remove them. The FM header should fit flush against the stock gaskets. The exhaust nuts should be tighten so that the end of the stud is flush with the nut. No stud protruding past the nut according to Jamie to prevent over tightening which will crush the gasket.

 

Also make sure the FM flange is actually in the bore and not hung up on the aluminum outside flange. Tighten evenly.

 

My FM pipes came with Cometic gaskets and headpipes installed easily.