my old panther has rattling cats. putting hand behind tailpipe i don't feel a lot of pressure. so I'm gonna remove them and see how bad they are.

I already put spacers on rear cause p0420/430. should I try to clean what I can and remove broken chunks? Gut/partially gut? don't want it to stink bad or be too loud.
also newest cheap cats on ebay are $80 each but they'll probably go bad quick, right? maybe this is easier