Aries muffler question

[Steve_Mack_CT]

Installing a new muffler, regular steel not stainless today. Decent exhaust manifold from what I can tell so far. Aries recommended their clamp and some sealer which I have. But I also have the little copper gasket. They don't recommend but what experience anyone else has had here would be helpful. I generally follow the manufacturer directions but I also wouldn't mind any experience based feedback. Got the sleeve also but not planning to use that as of now.

Thanks, steve