So you have 4bbl carbs on those 4.3’s? Most came with 2bbl and are rated at 190 HP. What is the current WOT these engines can achieve? Alpha 1 Gen 2 drives? Prop diameter? No marine growth on the bottom? Have you tried Quicksilvers prop calculator to see what it recommends? How long have you owned this boat and has it always performed the same?
1997 2400 SCR
5.7 Vortec / Bravo 2