You have to be sure no chunks of the cat strata get lodged in the exhaust behind the cat.
It's best to remove it completely and check to see if it broke up in small pieces that could get stuck in your pipe or muffler. If you can't break the bolts loose, spray them with PB Blaster & let it soak a couple of hours before you attempt to take it off again.
Depending on your state's inspection, you may have to replace it eventually. Be sure your plugs, coils, & wires are good before getting a new one.
There's a couple of threads to DIY.
Good luck.

 

Thanks big Cajun. Probably going to replace the entire exhaust system eventually anyway just wanted a quick temporary fix until I can replace the exhaust and coils and such.. Will post updates as I get