performance and bottom paint removal??

[seastrike]

I have a 78 20 foot master angler. Motor is a 150 e-tec. Boat has trim tabs. I am having the bottom paint removed, an was wondering what yall think this boat should do with a slick bottom. In the past with 2 people and a full tank it would do about 38-40 mph at 5500 rpm,depending on how high the seas would let me trim the motor out. With the new slick bottom what kind of increase should i see. Will it now turn more rpms with a slick bottom, i wonder if i'll have to adjust pitch or get a new prop??