The real answer to this problem is a 4.5-5" pitcjed 3 bladed prop or a 3.5-4" pitched 4 bladed prop. You would then reach WOT, attaining full HP which would increase HP out put and speed (to a point on displacement boats). Thrust would go way up, and fuel economy only slighty down. Another thing to remember, 4 cycle engines don't like WOT for long periods of time, so you would never cruise at 5-5500 RPMS or you would burn up the engine. But then 2 cycle engines don't like being run at below 1/4 throttle or they foul their plugs after a while. My engine does not twist, I have the bolt that holds the collar where the engine turns tight and I do not lube this point ever. If yours is twisting, clean out the grease here with some brake cleaner and it won't turn on you anymore, nor will it steer by the tiller well unless your a gorilla.
I will try the trick with brake cleaner.. the manual states though that the friction adjuster there was not designed to hold the engine straight when in use.
As to WOT... thats rough.. cause if I can't get about 40% more power out of the engine it will be run at WOT for 98% of the time as that is what it now takes to get the 5 NM against 2+ knots of current each way most of the time to get to where you can sail. Against the current over the ground speed will be 3.3 knots now. hour and a half trip or better one way. With the old 4hp 2 stroke I would be doing right at 4 knots over ground and I had to run it WOT to get that. Getting the new engine I hoped to be able to run it at about 3/4 power/throttle and get the same speed... sucks to be me... WOT and it is slower by a lot. Even when dropped down to the 6 pitch prop it is slower by a lot.