I once tried to up my nitro to 15% from 10% (in the NT16) and it just didnt want to know! It just would not idle for anything, yup I tried everything and in the end went back to the 10% and it was right as rain....wierd...[&:]
But after putting the OS 18 in, I would go back for quids.

EDIT: FYI I run 20% in both my Sav and the MT2 (since engine swap)