Hi, the nitro planes piper is a great plane. It flies very well, even in 18 mph winds.
I use a turnigy 28-26, 240 watt motor and 3 cell 2200 mah lipo and a 30 amp esc , 10x5 asp prop (hobby city. com)
Actually the motor produces 160 watts on 3 cell ful power and that is enough to do aerobatics with the bird.
I guess it will fly on 120 watts nicely. I want ot buy one more but they are out of stock everywhere.

Peroel