I'm trying to hook up my edelbrock smog tube headers and my y pipe, I'd just like to make sure about something before I bolt it all together and install my cat.

My understanding is that the ball/flange connections don't require any gasket, right? That would be the driver side where the header meets the y pipe, and the pass side where the bottom of the efe valve meets the y pipe.

But what about where the flat side of the pass header meets the flat side of the efe? It looks like there should be some kind of gasket there, but I can't find any part number of one. I know I've seen gaskets that look like thermostat gaskets but the the silver exhaust gasket material. Maybe I just use some kind of sealer, but then what kind? Does permatex muffler sealer dry so hard it would basically glue them together? Is the permatex "ultra copper" what I want? It seems like it would leak if I just leave this joint bare.