Keep in mind since it has over 120K miles and it being 11 years oil, the cat probably needs to be replaced anyway. When cat's go bad they don't always break apart. They can melt. This is usually because of to really rich mixture where it's burning inside the cat still. Also, check the rest of the pipe for dings and dents. A closed off exhaust tip will really back things up.
You can get a OEM replacement for $$$ or a generic for $. Sames goes for aftermarket. I replaced mine with a Carsound direct replacement performance cat. If the muffler is also original then you should be able to get the cat off without having to just cut it. There is a clamp and it's press fitted joint. If you do have a aftermarket muffler then most likely it was welded and you'll have to cut it off and probably get it welded on.
Before buying anything, I'd check the PCM for any stored error codes. Not all codes turn the dash light on.