Woohoo, there is not much that a YS cant solve. My Ultimate is a different machine! I got the following RPMs at 600 ft 80 degrees and Performance Plus YS20/20:
APC 15x10 8900 14.5 pounds
APC 16x8 9000 15.0 pounds
APC 17x6 9100 16.0 pounds
Thrust was measured using a spring fish scale. I am going with the 17x6 on my 10.5 pound CG Ultimate. All of my future engine purchases just might be YS instead of OS.