I flew mine with a TT 46 Pro with the regular muffler. I don't think a Pitts Muffler would fit.

The one thing I would do is use the aluminum engine beam mounts as a pattern and replace them with steel. This was the only problem I ever had with this plane after I beefed up the landing gear mount. The aluminum beam mounts will break. The landing gear mount was made out of wood instead of aircraft ply and split length wise on a bad landing.

John