Jack Plate on Triton TS17 Aluminum

[Micant]

17" Aluminum w/ Merc 75 Optimax. Porpoises really bad when trimmed where I think it should be (calm water). Trimmed down, no porpoise but serious loss of top end speed. Cavitation plate is at the extremest bottom of the transom. I think the motor may be too close to the transom and may be too low as well. If anyone is familiar with this boat I could use some input on whether a Jack Plate or motor elevation will help. Thanks!:wallbash: