Do not take offense to this Storm, I like guys that run the smaller props and get more rpm out of them... They give me practice when I come around to lap them... he he he... I did a lot of testing with lap times and my data recorder, there is no question in my mind the 9.25 is faster... I showed anywhere from 5-7mph faster and another 3mph faster than that with the 9.5nn.... that is in good conditions on the west coast... Even when I horsed the plane around with the 9.5nn, it was down to about the range of the 8.75, but then with a good lap, I would be right back above the best the 8.75 could do on my plane...
Rocket Ray validated what I see in qm in rpm, one prop peaking at 24,500rpm on the ground was 5-7mph slower than a prop that peaked 23,200 on the ground.... Rpm is not everything in my opinion and in all my testing in 428, the 9.25 is clearly faster... Just went 1:08 with it, the best I ever did with a 8.75 was a 1:13.... They do take some getting used to when needleing. I never peak it out on the line, I set it in the pits, shut it off and then start the engine on the line throttled back... I never go wide open until right before the flag drops, this seems to help a lot. Those big props can overheat the engine quick!!! So if you are not good at needling, I do recommend the smaller props because they are eaiser to needle and do not get as hot as fast....
P.S. In Hot Humid conditions, the 8.75 can be the better choice...