Most of the club members in my club run around 15% nitro. The heli guys run some crazy %s. But I run 15% only because of the 4-strokes. Before I got 4-strokes, I used 10%. I broke-in my old Irvine 15 years ago with 0% nitro and it tolerates 0-15% with only minor tuning changes required. I have not yet tried to see how low %nitro I can go with my 4-strokes. Might be a good experiment.