When I put the 40 horse on my 16' Lund a couple years back and maxed it out, it was initially horrible.
Yeah, I had to tweak the position of the motor bolted to the transom as well as the prop, but that didn't help.
My boat was so light for that motor it was literally hurtling out of control at top speed, porpoising even in flat calm water, and turning was a nightmare.
I put the trim tabs on and the everything was fixed. An added bonus was getting on plane twice as fast and at a much lower speed...