you will love the BIG BOY. i run a OS 91FX on mine with a 14x6 apc or a 15x4 wood prop and it does very well. it hovers a 1/2 throttle and has good pull out. if i replace my engine i might go to a 108 OS or maybe a 120 YS, but the 91 is doing fine. yes you need to cut a door in the top of the fus, it will make fuel tank install much easier. also use good servos, the control serfaces are large and they need some torque.

good luck

randy