OK I bit for those zippy copper header gaskets on ebay and got burnt. I installed them with my new Edelbrock TES exhaust on my 401 in the J-20 project. I have lots of exhaust leaks between the head and the header. I talked to a former edelbrock engineer who is a member of another forum and he said that the copper gaskets work well with the stock manifolds but not with the header style sealing beads. I guess he means that the factory exhaust manifold being machined flat and not needing a gasket from the factory will seal with the copper gasket while most headers are not flat and have a sealing bead. Anyone else run into this? by the way the Edelbrock gaskets are back ordered until 2/16