I just wanted to see what people suggest for best top end, speed, propeller for a 242 ls that has a single 350 alpha gen 1. I have a 17 pitch SS now and looking to upgrade. Any suggestions? I think this is the best one for now and im getting mid/low 40's. Let me know if I can do better. Any help is better help!

What rpms are you at at full throttle?

This boat with a stock BBC can only pull a Mirage Plus at 19P with a 1:50 drive. Your SBC is probably optimized at 17P unless you have more drive gear ratio. It takes a lot of power to push 24° at 5000LBS.

I agree with aquaforce. I had a 19 mirage on my 242 SS with a 350 mag and it was to much prop, I could only get 4200 rpms out of it.

Srdrago,

This thread posts many prop pitches/RPMs/speeds: 242 Speeds

Mine came (from prev owner) with twin stock 350s with Rochester 2 barrel carbs (260HP ea I believe). *It came with these:
Mirage Plus, Part #:48-13700:
Dia: 15 1/4.*
Pitch: 19.*
Blades: 3

I got only 4200 RPM due to the large diameter of the props. *See this thread for more details.

I replaced them with new Mercury Quicksilver Lightspeed (replaces Laser II) props, Part #: QS5072X.*
Dia: 13 7/8
Pitch: 21
Blades: 3

I picked up 200-300 RPM and 2-4 MPH. *

The next step was replacing the intakes, moving to 4 barrel 650 CFM carbs, and thru hull exhaust. *With the Quicksilvers, I got about 5100 RPM (58.6 gps).

I later tried 21P Mirage Plus props, but that was too much prop.

I am hitting around 4400 RPM with a 17 pitch

What diameter prop? Size matters.