Stock heads with new valves,springs,etc.

well 4600 with a 25 prop, something is wrong, you are 1000 RPM down, thats your speed loss...make sure no plug wires crossed, yes plugs wires, verify timing again at full advance, with a different light, if everything ck out there cut the oil filter open to make sure this thing is not eating its self up. If it made that power on the dyno and now in the boat won't turn 5500-5600 something took a crap...

I completely agree. But the only thing differant is the prop. You have your baseline with your old prop. So try the new motor with your old prop. That old prop may have been labbed or pitched. Even though you should be turning a 26-28 prop see what it does with the old one. After all it's just one nut right,,,,with a 25 you should be bouncing off the chip but I still say go back to the baseline. Also how do you know the Dyno sheets are for your motor?

Any way to post dyno sheet? How dramatic did the toque drop from 4500-5500?

To start with, put the original prop back on and get a base line. Hydromotive is more true to pitch and bigger diameter than the turd prop you were running before.

Have a rev limiter w/ that box ? If so, what chip is in it ?

Remember, MSD and others start randomly dropping cylinders here and there before the rpm limit you set to help keep you going over the limit.

Glenamy,The torque went from 592 @ 4600 to 536 @ 5550.Drew555 I don't know 100% if this is my dyno sheet other than my name and motor info on it.I was not there when the engine was dynoed.Is it possible to dyno the engine installed in the boat?If so,how comprable is it to being dynoed out of the boat?

Sb They didn't change the chip from 5200.The new box has a 4000,6000 or 8000 chip.I wasn't close to 5200 so i didn't even think twice about that.I will put a old hydro 24 pitch on tomorrow and put the 6000 chip in and run it and see what i get.

If I remember correctly, the chips are just resistors so you could remove it and eliminate that element

Totally correct.

If all pretty much is the same / stock (cid/heads/etc) on this motor but a larger cam, the powerband has simply shifted higher.

Many instances like this, the original 'best prop' will work just as well but now faster because it's being spun faster.

So many people thing they need a larger prop, but many times they don't.

Simple math syays if you can spin the same prop faster, the boat will be faster.

Only time to go larger on prop is if the 'new mods' spins the prop past the engine's usable rpm.

If you spin the original prop slower, well, you have a tuning, rigging and/or engine problem. Atleast the prop is removed from the equation.