Good sounding muffler for 225 cui

If you're going to replace the pipe, I'd go with 2-1/4" all the way back with the same size muffler, if your engine is stock. Are you running the stock manifold? If so and you have a reason to remove it, hogging out the exit hole to match 2-1/4" will help it breathe a lot better. I used a Dynomax Super Turbo on mine, it has a nice sound and does not drone.