RE: new YS 45 with tuned pipe
I have a YS 45 RE with a Mac header and a Prather marine pipe turning a 9x9 APC. From the plug to the apex of the pipe is 12 3/4". Sorry I dont remember the rpm's and my tach is not working now but it is scary sounding. My is currently yanking around a Direct connection Dodger. I had the motor on a DC F-20 years ago. Experiment with a 9x9, 10x8. I think I liked the 10x8 better on that airframe.
Cody