So i finally got a new prop and got a gps on the boat and got some numbers.
Boat: 1650 Xpress mod-v
Motor: Mudbuddy 35 hyper sport
Now i know this is not a true mud hull and when i get out of school and get a real job i will have one, but i realize this is most likely the issue. But i was only getting 23 mph by myself in the boat in deep water. Kinda disappointing. i figured id be getting 27-28. However i was surprised when i packed the boat down with 5 people (approx 900lbs) plus a blind, full fuel, and two batteries i was getting 21 mph and getting on plane pretty quick. What could cause the slow speed with a light load. I was expecting 27-28 light and with near 1000lbs to not even plane out.

I have a WarEagle 1648 w/ MBHD Sport 35....pretty similar boat. I can't tell you why you are getting the performance you are getting but here is what I get. I can run about 26mph in open water with just me a small amount of gear (no dekes, guns, bags, coolers) in the boat. With 4 guys and a small amount of gear, I can't get on plane.