Between here and the performance shop I work with, it's starting to become a consensus that I'm over propped. Going to try a set of 24s or 26s.

To the question above, yes in natural it will rev to 5000rpm.

Weren't 28's the stock props on that boat? I think it's time for a compression test and leak down.

I'm going to disagree with you on this one. What a motor does in neutral and what a motor does under load is two completely different things!

Like i said to the previous post.. what a motor does in neutral and what it does under load are two different things.

Your issue is NOT the prop size! Could your prop be damaged? sure. But it is not the size. These boats came with 28's and like I said i have the same exact boat. You are down on power... big time.

It's suspect to me that both motors would have compression problems uniformly.

Same hours on both, that sh!it silent thunder system, and or bad manifolds. I've seen it before.

Leak down test!!! Will tell all

502s with 28P at around 4400rpm I get almost 70mph with a normal load.

A engine that isn't running correct may still spin 5g with out a load. A compression test and a leak down will tell a huge story as to what is actually going on. This is a inexpensive test and will save a lot of time and money vs. trying different props and may save from further damage to cylinder walls if you are having reversion due bad exhaust or internal leaking.

Being that you run in salt water It is very possible that you have internal leaking due to exhaust issues or possible head gasket. Witch leads to low compression either thru the heads/valves or cylinders. Just speaking from experience. What exhaust are you running?