I run Stage 8 and like I said they are a pain, after cycling the engine several times till you can't tighten the bolts anymore with a wrench you than have to file the half moons so they fit tight against the header tubes so they don't start to back out, I filed all but three,I also had to dimple a few tubes so that I could get the moons to slide on because of the tight bend at the header flange,not good if you have coated headers, they work fine but a lot of work,look at your Summit Cat and check out the split bolt type, they have a split bolt with a allen set screw in the hex head,once you got the bolts tight you run the allen in and it spreads the bolt so that it can't back out,either way use a dab of anti seezees on the bolts.

I always tell people gaskets will not seal and you will have a leak if the surfaces are not flat.  I tell people to place any mating surfaces that have to be sealed against a truely flat surface and run a .004 feeler gauge around it.  Usually if its off more then that it will usually leak.  If the surface is out then take it some where so it can be milled somewhere in the .002 to .004 flatness and you will have no problems with any type of gasket.