I did, I cut about 4 to 5 inches out of my muffler, then used part of the piece removed as a second wall to rivet the muffler back together. I dont know if i have a really good shot of it, but will post some later. Improved annoying the neighbors also feels like it just really opened up the bike, low threw top end. Added quite a bit of torqe.
Muffler that I modified was the stock one.
These are the only shots that I could fine so far, I will try to take some better ones for you.