I was told that your motor cavitation plate needs to even with the bottom of your boat and one inch high if your running an stainless prop ? I have an 20 ft roughneck jon with an evinrude 140 and when I installed the motor I put it all the way to the stops on the transom. Right know I have mine about 2.5 inchs below the bottom of the boat. 2 problems I have, one is when running around 25-30 and very little trim, when I hit full trottle the prop will cavitate, secound is I cannot trim very much before I get to porpoising. I now I am probably a little over powered. Do you think by raising the motor will help or is going to be trial and error. Also would the cavitation plate being below the boat cause some drag ?