Can't believe no one has replied to this...
Yes you can rip the guts out of the orig can. It will be louder, but you don't have a nice pretty can. I'd go a after market can and race cans are straight through pipes, so they are a shite load louder. Not exactly legal, so be prepared for your insurance company to wipe you like a dirty nose, if they cotton on. Always stopped me
Got my last one off ebay second hand, but in great condition.. Less than Half price and no damage

So check ebay / your local wreckers and you should find what your after...
NB: keep your orig can, for resale ????