About 10-12 months ago I rebuilt the exhaust on my 72 K5. I installed Hooker headers and Flowmaster Delta 40's. It is dual exhaust with 2-1/2 inch pipe. As you can guess, I cannot get the headers to stop leaking and it is very loud! I have tried Percy aluminum, copper, cork, paper, and pure silicone for gaskets. It didn't leak when I had manifolds. I am now using OEM original manifold gaskets with "Red" high-temp silicone. This last fix works better, but still leaks. My question is, what methods do you guys use to find where the leaks are coming from? Does anyone else have any more techniques for leaky headers that I haven't tried? I have searched the forums and have seen this problem everywhere, but nobody comes back and tells us what cured their leaks. I am at wits end with this thing and am ready to go back to manifolds unless someone has a miracle cure.