Exhaust Upgrades?!?!??

I'm looking to upgrade my Catalytic Converter on My 02GT, The current one which i only had replaced a little less then a year ago is already going out on me. I was wondering if anyone knew of a higher performance Cat i could get to put in the car? My options at the moment are to get an OEM if warrenty still covers it, go high performance aftermarket, or go to a straightline pipe. I've had the car checked out everything runs fine, it's not running rich or anything. But i've noticed now that i do a lot of highway miles this has happened. Back in January i was getting 30+mpg highway now i'm lucky if i get 20mpg highway.

any opinions on what should i do?

Try xtremeflow.com they should be able to help you with a high flow cat for your car. Also, you may want to check Andy's Autosport or PFYC for other exhaust parts for your Grand Am.

magnaflow also makes one for our car that's high flow.