I was wandering how to dramatically quite down a 212 predators exhaust noise. So I can talk and hear my Passengers. This thing is going to be right in my ear.
I could only suggest running a long pipe away from your ear, Just like a header we run, but then put the muffler on the end of that.
This is for the rail rider? put a small car muffler on it. It is not like you are looking for performance, just steady chuggin along right.
Putting the muffler in the middle of a long pipe would help even more. I think the Briggs muffler from ace hardware is the best deal out there. Cheap and threads into 3/4" conduit without a die. The perfect size pipe and cheap to bend if making your own header.
Maybe look for generator mufflers? Kohler also makes some nice mufflers.
You could do what Jfive suggested with the briggs muffler and sleeve a larger pipe over the muffler. So the muffler will retard the noise, and the larger diameter of the pipe will tone it down.
I use one of those bullet mufflers in a slip-on config and there is definitely less snap but it is still pretty loud.