provided the insides are empty (they will be if its all smashed as it will blow out), you have the best option already; you wont get busted so much by the cops if they pull you over (decats are illegal for road use).
However most of the time cats dont completely break apart (and in some cats there are 2 seperate honeycomb sections), which ends up blocking the pipe and thus reduces performace. I remember when it happended to my car years ago, it suddenly lost all power as the pipe got blocked.