I'm running a OS .46 AX (fx is not made any more I think) with a 11x6 MAS prop. Members at the field have said that the OS .46 might
be a little too much for a trainer but I don't think so. Actually, my Arrow is 1/2 trainer and 1/2 aerobatic in that the wing is semi symmetrical. I was flying at about 1/2 throttle. Full throttle and the plane is a rocket that you can shoot up straight verticle.
Its nice to know the power is there when you need it.

Dave...