ok got a 23 Daytona s BBC stock bravo going 80+ just built bravo w nanose gearcase is 2 inches below can I expect to c less rpm from loading prop thru hydrodynamic efficacy ??? I know is I need a imc o but not now running it at 5200 spins 5500 into the wind

Running a 28 bravo prop

I doubt you will see any rpm difference.

That is good in feeling blowout a little at wot hope this helps