You should be able to use either the metal gaskets you described or the
asbestos ones that S & S provides (don't use both!).  Are you sure that your
connections are tight at the flanges?  Maybe you are using bolts that are too
long?  Or try to put your hand around the joints with the car running and you
should be able to feel any exhaust leak.  That way you can pin point the
leaks and try to fix them.  Hope this helps.

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242