Paul,
        Other than Tracy's PSRU what options do I have??  Do you have a preference and why??
At this stage interested in a muffler, but will confirm.    Neil Unger.

Not many options for PSRU's.

I was in a motorcycle shop buying parts for our Ninja motorcycle
and I noticed the forged aluminum rear cog belt sprocket on a lot
of V twin Harley motor cycle copies. That may make a good part
for a belt reduction drive. You might need two side by side.
Ken Welter uses a 3:1 belt reduction drive on his Coot.

Paul Lamar