If you keep the pitch the same but decrease the number of blades what outcome can you expect?

Easier to turn the prop, so you should plane faster and be able to turn more RPM? That should translate into a little more top end, right? Or am I missing something?

no one?

Not that simple , many variables come into play , ie : propshaft depth , steps or no steps , weight , power etc .

I'm not able to spin my engine as high as I should be (4200 rpm ish). I assume that it's because the prop is too much for the power that it makes. My prop is a 23P 4 blade. I found a used 23P 3 blade for $100. Would it be worth it to buy it and swap them out? I'm looking for a little more top end.

I don't know propshaft depth, it's a factory 24 Outlaw evidently the X dimension on them is pretty low. No steps. Boat weighs about 4000 lbs. Stock 330 hp 454.

With that weight / horsepower / drive depth combo , a labbed 21
mirage may be the way to go

If everything is the same except the number of blades I think increase of 250 ish rpms

In most cases, a 4 blade will plane off faster than a 3 blade. What engine are you running? We need to know the operating range of your engine. What is the 3 blade you are looking at - make/model? The same goes for your 4 blade. From 4 to 3 blades will give you between 150-200 rpm's. Maybe more, if you also decrease dia. I would try a 21 Mirage+.

Also consider the diameter of the prop, larger diameter=less RPM. Opps just read the post above mine......

I believe a stock 7.4 330hp should operate at about 4600 rpm. A mirage plus will carry the bow higher than just a mirage.

Based on conversations I have had with owners of Outlaws, they run better with 3 blade props.