Yeah those adapters are a joke. I could go to a 3" pipe because I have a 505cid in the works but the 2 1/2 is plenty I think. I bought 1/2" thick stainless steel collector rings so I can sandwich the RemFlex gaskets. I know all to well about crawling under the car for an exhaust leak repair. I figured with the 1/2" thick flanges, I would be safe for the entire life of the exhaust system.

I'll check out your links and see what i can gather.