Then here is a question for you Nitro, do the bigger STs want the FAI?? I'm running 15% and then high end will lean out but you can back it out a lot before it goes fat. I have never fooled with there bigger engine, the 2300 runs great but there is just something odd about the carb settings?? I know a lot of folks just put on a different carb but this was a free plane and engine I have given to two of my students.