So the boat is wet slipped? Is it bottom painted? Regardless is the bottom clean? A dirty hull witll scrub speed big time. You said the boat won't even run 40 MPH. What does it run at WOT on GPS? What RPM are you turning at WOT? You may have other factors at play here besides the prop. Does the boat have trim tabs?

No paint on the bottom. Yes boat is wet slipped and yes the bottom is a mess but enough to cause a 454 to struggle even to get on plane and take 15mph off the top? I wouldn't think so but I know there are perhaps a few factors at work. I had seen the bottom on land in early spring before I bought it and the bottom was spotless and had waxed it with floor wax Then the seller put it in the water and I bought it. Been in the water now since April.

It'll get to 4600 RPM if I wait a bit. No trim tabs.

I had a 3 blade 23p mirage on my 230 and was pretty satisfied. Original 330hp 454 would pull a skier and top out at about 50-52. Non-gps speedo wishfully showed 55. Sorry don’t recall if regular or plus version.

that was just a guess. I had a 260 powerquest with a 21 pitch mirage plus 454 mag. So I figured your boat should have a 21 pitch prop also. You said it was a slug out of the hole, so you would go down in pitch. You said you wanted to try a 4 blade so I said 19 bravo. If they dont make a bravo in 19, I would try a mirage plus in 19. Its pretty much all guess work without knowing your pitch now.

From a buddy of mine that owned a similar boat several years back:

It 1992 23’ Powerquest Conquest Cutty, 8' Beam, 330 Hp Merc 7.4 Liter, Bravo 1 Outdrive, Stainless Turbo 21" Prop.It ran about ~55mph on a good day. Why?

Thanks for asking your friend about this. I really appreciate it. That boat looks more like mine than anything else I've seen... Seems like no two PQs are exactly the same.

Remembered the survey had my current prop info:
Stainless, 3 blade, mirage 48-137-A41-21P

Says I have 1.5:1 gear ratio as well.

I would not spend a dime on props until getting the bottom 100% and then running it again.