Any 40 or 45 will fly the Tower 40 Kaos just great. What is this "60 size plane?" The Tower Kaos is not a 60 size plane, and with a 45, it is a very manuevarable plane and with full power it is fast, and has great vertical.
I have flown Kaos's for many years, and from several different manufacturers. I almost always have a Kaos in my hanger. I have read that it can't do a knife edge (not true), that it is
a poor ARF (not true) poor covering (not true). I am always amazed when this plane is criticized, since it is easy to build, has a very reasonable price. Just one of the best planes available
for a sport stunt airplane.