[cobrashoch]

A old hot rod trick when the mating surfaces are rough is to use two gaskets and studs. Done this several times in the past and it allways works. Makes it simple to tighten the nuts up from time to time to keep those pesky leaks from coming back. As for how long they last, my neighbors car is a daily runner w/130K miles on his headers using Hooker supplied gaskets. Caution - You will loose that hollow header "sound" using this method. It really quiets them down. This is the only way to fly in my mind on cars that have side pipe attachments, as silicone will eventually work itself loose with side pipes that force header flex from engine torque rollover.
cobrashock