The ring...it's the, well, I guess you could call it gasket...It's actually a compression ring for the cat/test pipe, similar to what's used on the JG header to connect the two halves of the header. If you pull off your exhaust and look at the flange on the cat, you'll see the same ring, assuming you have a stock cat, or well made aftermarket one. I left the one that came on mine on it, as I'm sure there is an easy way to get the old ring out, but I really didn't have the patience, and after a little fidgeting, I gave up...No exhaust leaks, so I guess I'm ok...Any way, I really don't have a better explanation than that....

Later,
Aj