i upgraded to a yamaha 60 2 stroke and took it for a test run today. i have a 1648 grumman semi-v hull. weight? maybe 500-600 lbs. not sure just a guess. the motor has rpm range of 5000-5500 and a 19 pitch prop. wot rpm's hung around 5500-5800 and top speed was 38-39. hole shot is tremendous! should i go with a 21 pitch? if so, what changes could i see? aluminum or stainless? name brand prop? there were 2 people(430lbs.),2 batteries, trolling motor, 2 coolers, and fishing gear and it gave us whiplash out of the hole, so i'm thinking higher pitch. figured i'd ask the experts.