nothing wrong with ap 15 or 09. had the 15 in a h.o.b. .20 size mustang, it cowled great! ran an 8-3 on it. a freind had the 09, it ran well, but 15 was about the same size/weight. I fly a lot of norvels myself, but from a scale standpoint the ap's are easier to hide with the rear mounted mufflers. I have had really good luck with the phasor motor by hobby lobby, it performs great in my zephyr on a 6-cell car pack. I am mainly a glow guy, but for a scale twin I would go with that! A caribou or twin otter w/ two of those would have plenty power, and be reliable. Hope this helps, wildfred.