RE: US Engines 41.
I had a US41 in a TFGS Mustang... Not a powerhouse, but dependable as sunrise... A XOAR 20 X 8 prop, or a 19.5 X10 Menz gave me the best performance, in the 68 to 7000rpm range.. The Zinger and Top Flite props gave much noise, but little performance..
Just a solid, dependable old gasser, in the Quadra family..