Sorry to resurrect an old thread, but this seemed more logical than to start a new one.
I'm currently changing my stock exhaust out for a Brock's Short Meg 2. I could not for the life of me figure out what the exhaust header gasket looked like (I was suspecting some kind of rubber o-ring), but upon searching found this thread. The part number mentioned above (18291-GC8-000) and the eBay link
leads me to believe that this metal looking ring is my exhaust gasket:
This is what I'm looking at in the service manual in case someone needed clarification:
If that's the gasket, it seems to be stuck down in the exhaust port. I think I should be able to just mount the exhaust header onto the engine now, correct?
It's a 2015 w/ about 70 miles on it. Thanks in advance!