the Roto 35 -
nice engine very sturdy design - easy to run very good power - best props - 20x8 or a wide blade shorter prop that loads it into 6000 rpm range
I have run it on Mas Scimitar 18x10 - over 8000- that is not enough prop.
the little muffler is also strong and light and works!
Included alum beam mount is nice -but I would opt for a good maple beam setup in the Ziroli