25' four winns vista speed
 

running the Vista (appox 5000 lbs dry) 454 cc, Bravo 1 outdrive, with a 15 1/4 x 21'' alum prop boat runs 32 mph at 4500rpm. is this the best I can get out of this set up ? should I try a different prop if so what size . Now out of the hole OK but want more top end.

Try a GPS instead of the speedo. If your turning a 21' prop 4500 rpm thru a Bravo with 1.50 gears you should be doing more than 32. If the GPS agrees with the speedo...unhook the trailer from under the boat:eek: You should be in the 40's at that RPM with a 21"prop.
Good luck

For a comparison, mines' about the same weight as yours (it's not a go fast either) with a 7.4 MPI, BIII spinning labbed and cupped 26" props and at 4500 RPM I'm running over 50 MPH. To run 32 MPH I'm at about 3000 RPM.

The 7.4 is slightly modified but the props, I would guess, are about 27" considering the cupping. I'm thinking you must havea misreading speedo or tach. Or you really did launch with the trailer. (just kidding) :D

I will check it with a GPS (after I unhook trailer and place it in the water) Thanks Mopower you are tooo funny! Thanks to you to SeaRay Jim
I hope you both have a Great Day ! Jo