I did mine, it will take you some time.
I would invest in the largest drill bit you can get and just drill holes in a cirsle inside of the cat. Once you have done that then knock out the center section that you drilled. Now comes the fun part.
Take a long flat blade screw driver and start to work your way around the eges of the remaining cat that are left on teh walls of the can. I started and knocked sections out, then turned the pipe upside down and knocked out any of the loose debris.
I used a pair of long needle nose pliers to pull out the large pieces or strips that broke free as the material the cat is made out of is kinda sharp on the edges. Just keep working your way around the outside of the cat core until all of the remaining cat material is gone. Once it is all out turn it upside down and shake until you can shake anymore. Stuff will come out both ends of the pipe once you have it all broke out.
i shook mine until it was all gone and there was no more dust coming out of the pipe. I also thought about using a hole saw, but I wasnt sure if the saw would be able to all of the way through the cat and exit the other side. The cat is about 4 or 5 inches thick.
It will take you some time, maybe an hour or two. I got mine done and put back on. It is not alot louder, but it does seem to rev a little faster. I also dynoed mine afterwards and even without the cat the bike still dynoes 146rwhp with a perfectly flat 12.5 to 1 A/F.
Ivan said if you can get one in the you can use a hole saw to cut through the barrier inside of the pipe to make it a straight through pipe. The stock pipe use chambers to divert teh air flow through the cat and then into the exit chamber.
I hope this help.