When I installed my headers last time on my SBC, I used the copper gaskets, and made sure the o-rings were facing out (header side). However, my headers leaked...I don't know if they are slightly warped or what. Anyway, I have heard of doubling regular header gaskets...can you double copper gaskets as well? And if so, should I use exhaust puddy, and how much. I would appreciate it someone could help me out on this one.