First post on this great site.
My buddy has a 87 24' baja force 235 with a 5.7 liter and it doesnt seem to pull enough rpms when running down the lake. Idles and revs good but doesnt have the take off and top end as it should and i mean like 40mph with 3 people. Is there just not enough motor or what other things could cause this. Im not sure which prop he has but its 3 blade. We are both new to the boating world but we are trying to figure it out cuz it sounds really but just has no go!! Any help is greatly appreciated.

If the prop has been changed to a to big of pitch prop it will not get the rpms and take off would be bad. I take it the pitch is not stamped into the prop?

You are definatly underpowered, most of those came with the 330 or 365 HP 454's. If its a stock merc 350 it most likley it 260 HP. You probably need a 17 or 19 Mirage 3 blade, you should spin it up to at least 4600 RPM. If everything is dialed in you should be able to hit 50 on GPS.

Ditto.

I have the same boat, and mine started life with a 350 Mag/Alpha. I saw a speedo indicated 53 MPH when I first got the boat, with a half tank and 2 people. GPS later confirmed that speedo was within a MPH or two of actual. I think it had a 19-inch Mirage on it originally. If that motor is running right, you should see around 50 with no problem.