Lude Generation

Have a check, and make sure they are bolts. I replaced the midsection on my mum's Accord on Monday night and cut them. They then turned out to be studs, and very much a part of the cat

If they are bolts, definitely cut them. Save you loads of bother!

My cat had studs. JDM import.
Try wire-brushing all the rust off and soak overnight in penetrating oil.

IIRC the studs can be pressed or bashed out. A big bench vice and a socket or fat washer should do the trick. If you bash them out be sure to clamp the flange in a vice first so you don't rattle the inside of the cat to bits.