Exhaust problems

Problems...
-Cat is now clogged at 87,000 miles.
-In the past I have had both sides of my exhaust come apart after the flange (flange separated from pipe at weld on pipe downside of manifold) Both sides have been rewelded but now the driver side has a whistle effect.

I'm guessing that my air/fuel ratio after the supercharger install may have been a little fuel rich and had caused the clogged Cat. But I am unsure why both sides of the exhaust have sepparated after the flange. Motor mounts seem good.

So it is pretty much time to redo the entire exhaust system so my question is what is out there... Anything worth anything in the aftermarket... high flow cats, headers, etc.? I have the PV2 and plan on re-using the muffler in my new system. What would you suggest? Any insight on my exhaust problems? Sending it to a shop this week and am trying to come up with a game plan on what needs to be installed/bought. Too cold to want to work outside on my own :(

Thanks in advance for any help/advice,
Alan

My cat clogged COMPLETELY shut at 68,000 miles. Replaced free under the Federally required 8-year warranty on emmissions equipment. Dealer had to use an aftermarket cat as all stock OEM cats are on back-order to Japan; I didn't have the heart to ask the dealer to use a hiflow cat ;) .