I have a 92 accord with a an aftermarket exhaust system. Everything works good but there's an exhaust leak where the header and downpipe meet. When I received the header and downpipe it didn't come with a gasket for the downpipe and header, just the exhaust manifold gasket. I tried using gasket maker but it did last long, I assumed it wasn't for an exhaust. What other alternative can I use that would the same as the gasket I need

 

usually aftermarket things are designed to work with OEM gaskets. See if your old header gaskets fits. And buy one from Honda dealer.