I couldnt find any previous posts on this, so ill be a dummy and post another one!

Has anyone shortened a 99 CBR900 muffler? Ive got a stock one, and I need to cut it to get true 12's (at the moment I have 11.55's lol). Im planning on cutting the end off, then cutting a few inches off the length and then rewelding the end back on. My question is what baffling is under the mufflers skin? Is it just a perforated core and wrapping? Or is it more complicated tubing etc?

Any info on this greatly appreciated.

Cheers,