ORIGINAL: planebuilder66
The .074 puts out as much power as a 10, but the .15 flies it better than the .074, plus it's a cheaper motor to buy, the last time I checked the .074's are going for around 100 bucks, plus, the plugs are expensive, the cheap magnum .15 is like 60 bucks, and has 1.5x's the power.
My buddy is using 30% nitro in an OS .15 la and it has unlimited vert. 8x4 prop. One thing I would suggest when running bigger motors is to use heavier duty control horns. The one on the elevator failed.