Mike,

Exactly so. Yes, the higher nitro will give some more top end, and a better idle. Define "better"; mine ticks over between 2000-2100 with the nylon 13x6, and was down to 1900 with the 14x5 wood. Mine is still new, and I still have it quite rich, so there's no point in looking at the static top end rpm yet. But it has plenty of power to make the model do what I want it to. So what more do you need?

All of this is on 15% Cool Power. Mike, many US modelers are in love with 30% nitro fuel because it nearly eliminates the need to fine-tune an engine. I ran it for years in my helicopters, and the few times I tried it in my airplanes the performance increase was quite noticeable. Fine; if you want absolute speed, and don't want to take the time and trouble to dial your engine in on lower nitro, go for it. Personally, I got tired of paying over twenty dollars a gallon for the stuff, so I went back to 15% across the board and have been quite happy.

I'm with you; who needs the higher nitro? I do think the smaller YS four strokes are happier with high nitro, but they can be made to run satisfactorily without it.

Steve