Thanks for the info, Since they have mild compression,are they not a good candidate for a performance plane? My cowl has limited space and this engine barely fits.If I go bigger then I will need to do major cowl mods. Do you reccomend another engine in the 25cc range with better power to weight performance? I have been hitting the saw shops and there are a ton of trimmers and blowers to choose from (most are free). I would rather convert my own instead of buying a new engine because the gas engines designed specificly for planes are rediculously high.