I've been flying H9 Ultrastick 40's for about 5 yrs with Saito 56's. Primarily APC 12-6 but liked the way the APC 12-5 was made compared with the 12-6.

I have eventually changed to a Turbo muffler on the Saito 56 and went to a APC 13-4 prop with maximum rates on the controls and 60% exponential. I'm having a ball