Question to all the welders out there!!!

This question should be posted in the related forum, but welcome to the forum! You are in a wealth of knowledge around here.

If I were in header leak city, the first place I'd visit is a tight fitting tube area. Check your tubes and make sure none of them are contacting the block or any other components, or binding with the exhaust system. Disconnect them from the exhaust bolt flanges to do the gaskets.

If they are not sealing on the copper gaskets, pull them off and examine the carbon pattern on the flange, to determine where they are leaking. That can tell you if one area or a lot of areas are the problem. If it is more than one area, it might be tubing interference. If it's isolated, you could have a slightly warped flange that could be filed straight.