Back when I was a kid, you ALWAYS mounted the head exhaust pipes to the Fentons with doughnut gaskets. ALWAYS. They even make two types of doughnuts, the kind for the flat flanged front header used with a flared pipe and the beveled doughnut for use with the beveled rear header which also uses a flared pipe. Most muffler shops have the doughnuts - I think it's a Fel-Pro gasket. Unless a muffler shop has never put dual exhausts on an inline Chevy or GMC six, they might not know that.
Last edited by 6cylindersovertexas; 12/27/2010 11:24 PM.