Make sure you wear and mask and don't breath the dust. I have been told that asbestos in it. They are getting away from it but that is what the exhaust guys tell me. IMO, if you knock the guts out, once the exhaust hits the gutted cat, it doesn't have a smooth exit (unless you weld a pipe inside) and it may actually hurt the flow. Also, I know a guy that did it and it didn't sound so good. Either weld a pipe in or get a o/r and do a simple bolt on.