You should be fine removing them. There is also a heat shield on the floor and if anything, you would just get a little more heat in the floor boards but nothing else.
I woulnd't say the cats are cooked for sure, I had the heat shields on my fox body start rattling until I tore them off.
Heat shields will sound like someone tapping on a shovel head and will make a TING TING TING sound where a cooked cat will sound like a bunch of marbles in a tin can rattling around. They sound somewhat similar, but hopefully that even made sense to begin with lol.
Easiest way to tell is to jack up the car and start it up to see if it rattles. If not, tap the cats with something and see if they rattle and just yank them off. I took them all off of my fox body because 2 of them rattled and I never had any issues after taking them off.