So far so good. I am still breaking it in. An excerpt from the manual indicates they have planned on people using %30

FUEL
Total thickness of head shim
Under 20% Nitro
0.3 mm
25% Nitro
0.4 mm (±0.1 mm)
30% Nitro
0.5 mm (±0.1 mm)

It appears that it is okay to run the 30%

EDIT I am using an OS 8.. but don't follow my example. This is only my 2nd engine and my first engine, the k 4.6 lost mad power on the start of the 3rd gallon.