Ventilation Problem

I have a 1995 16 ft Tracker DC DV. Since repowering to a 50 hp 4 stroke Merc, it ventilates very easily when in a "trimed up" condition.The slightest ripple on the water, or the slightest turn of the wheel causes ventilation. (prop spinout) Lessening the trim a little, cures the problem, but I loose a few MPH. What make it a problem to me is that before the repower, it didn't do this w/ the 60 hp 2 stroke Merc that it came w/. The motor is all the way down on the transom, and the motor ventilation plate is even w/ the bottom of the Vee. Any ideas for remedy ?

Rich