Ok, here's my 2¢ worth. I actually learned to fly on the Tower Trainer 40, and it had an OS 40 FP, which would be the equivalent of an OS 40 LA. I learned on that plane, and actually have taught 8 or 9 others on that plane. It's got 600+ flights on it and it's still flying to this day. The engine is to the point that I can't start it with a chicken stick anymore, the only way I can get it to start is to put an electric starter on it. So....... a 40 is more than enough for it. Too many people these days think that "bigger is better", which isn't always true. If the truth be known, a smaller engine on a trainer can actually be a good thing. Because the student learns to fly the wing, and not flying the engine. If you put a 45/46 on it you will have too much power and spent most of the time at half throttle anyway, but if you learn to rely on massive amounts of power to get out of trouble then you never really learn to "fly" the plane. But with a 40 on it everything you do will be on the wing.

And if the truth be known, my Tower Trainer with the 40 on it will do just about every maneuver that I know how to do. So the 40 isn't really "underpowered" like some will try to lead you to believe.

Hope this helps

Ken