RE: More control
I had handling problems with mine once it got broken in and I started putting larger props on it. Jerry Dunlap told me about placing the weight under the box and it helped. It must be that it's nose-heavy out of the box.
That engine has a lot of torque for its size as my son kept sneaking bigger props on it and it was turning most of them but didn't notice any real gain in speed. 40mm is plenty big enough for this boat but 37 or 38mm props would be a better choice to place less stress on the engine and improve handling.