Gy6 exhaust gasket
 

Looking for opinions...which is better, a full flange gasket or the copper donut that fits in the groove on the head?

I prefer the full gasket over the ring gasket. But that's just me. It's just easier to install and I feel there's more surface covered. I'm sure there are others that prefer the copper ring because it's more solid.
I've never had an issue with either though.

Thanks. That was my take on it too, that little ring is a pain to install, and the full gasket covers the whole flange...

I run the flange because my head is ported and the ring doesn't fit anymore.

I used that "ultra copper" flange gasket maker. It seems to work fine on my helix 150cc.