Have to agree, your 4600 lbs, my Rinker is 4200 lbs and I have a 300hp 7.4 carb, and I can do 60 mph. Yours should do at least 50 mph with 385hp
Have you tried weighting the hull to see if its water soaked?
I have not, I know I am definitely due for a new bottom paint job at end of season. Would be a good time to have hull checked.