If you're getting splashing off the leg back into the boat, your motor is likely too deep. At speed, the larger (anti-ventilation) plate on the LU should be just at the waters surface (or possibly slightly above - depends on how the motor reacts in turns.) Be aware that weight distribution will have an effect on where the AV plate rides, too.
General starting point is to have the AV plate even with the lowest point of the hull bottom, and move it up incrementally from there until you start blowing out in turns. You may find that +/- a couple of (or a few) inches will be right for your boat.