Also check your header flanges with a straight edge. You'll probabaly find that they are not true. I used #36 grit on a longboard, and a lot of elbow grease to true up my headers' flanges, then dusted them with #80 and #100. As tohcan says, high temp rtv works well with paper gaskets. My headers are super miserable to install fasteners, so I glued the gaskets to the header, and let it cure overnight. That way, I didn't have to chase gaskets floating around in a blob of sealer. (I cannot comment on other brands, but with the old style hooker comp +, the 67-81 versions, it would turn into a real mess to float gaskets in sealer while installing. Install the header to the engine with rtv between the gasket and engine ports, and draw the bolts to just snug. Let it sit overhight; then, put the mojo to the bolts. The headers are totally leak free, something that I have never had in the 30 years of running headers on a fgf.

It has only been one season, with super light use, so we have to let the timeline run a while. In the past, however, the always leaked, and didn't take long to blow out to the zit-zit-zit syndrome. My mufflers are more quite than most, so header leaks sound exponential.