first time bass boat owner here so i'm not very knowledgeable on jack plates. my boat is sort of an older one an '85 procraft 17 1/2' with a 150 merc on it. very heavy old thing 1700 lbs w/o motor. it'll about 50 mph with 2 people and full of gear. are there any experts out there that give somewhat of a good guess at how many mph i'll gain from a jack plate? thanks