I have that exact rig, and with a 21″ SS I’m topping 55 MPH fully loaded and two heavy weight walleye chasers. With only myself and 1/4 tank, I’ve nipped 60 which is damn fast on water for me! She’ll cruise a comfortable 43ish all day long. I know this might be a late answer for the poster, however if someone else is wondering, I hope it helps.
~Tight Lines~
I have a 2012 1975 IFS with 225 Pro XS, kicker, 5 batterys, terrova up front. It will normally run 55-56 mph. Its best speed was 58 mph. I run a tempast 2 in a 21 deg pitch prop. Im also looking at selling the boat. Time for a new one for me.