Cats are there for a reason and should never be removed for street use.
Now ethically if one was to gut the cat. He or she could use a large speed bore bit like a 1" with an extension so they could get up into the pipe. Let her rip untill the grinding stops and vacume out the peices. beat the crap out of the cat and repeat this will dilodge any big peices. vacume again and you should be good. Get out all the goodies inside because if it clogs up in the muffler you will know shortly. No I would have no first hand experience with such a practice as since NY requires cats visual and snif testing. But If you can locate a "quality" inspection station you will be supprised to see what passes.
LOL.