Sorry folks - should have mentioned the bike. Its a stock 1995 EVO. The gasket was a HD item (not sure if the correct one) - it was tapered/beveled on one side and square on the other. I fitted it with the taper facing out to mate with the header pipe.
Did you use the flat style gasket or the cone style ?
So.
Putting the gasket is n the freezer overnight helps with the installation fyi.
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For what it’s worth here is a link I used when learning how to change the pipes on my fatboy Lo.