WAS: Header Gaskets and Copper Washers

I have third party exhaust pipe on my bike (a 1995 KAW Vulcan 1500).
There's a lot of play around the header in the exhaust port. I used to
be able to get a thicker/beefier metal ring crush gasket that worked
better than the narrower and less substantial stock gasket, but lost my
source.

So I went to a couple of local auto parts store to look for a "beefier"
metal ring header gasket. The counter men in both stores were quite
helpful, but could not come up with a gasket that was 52MM outside
diameter (what they had in stock were ring gaskets to wide for the
exhaust port).

At the second store, however, the counter man brought out a different
style ring. It had an inner ring much like the rim on a motorcycle
tire. And where the tire would go on the rim, there was a mutilayered
material made up of metal alternating with what the counter man guessed
was Kevlar. They were also bigger than stock, but looked like they
could be easily ground down to fit. Since they were relatively cheap,
I bought a couple and ground them down just enough to drop into the
cylinder exhaust port. I still have to put the engine back together so
I haven't had a chance to see how these different gaskets will work.
So I'm asking here if anyone has used a fiber gasket like these and how
they've worked for you. Any gotchas? TIA for your tips, suggestions,
comments.

Manjo