As your not sure on the prop, consider calling Sunsation and ask them what they used. Generally, if you can get on plane with a 3-blade prop, you will scrub top end speed with a 4-blade prop; however, the holeshot and mid-range improves with 4 blades. If your RPM is close to your goal with the 3B 24, then compare that preformance to a 4B 24.

.....
 

Found my problem.... Of all things, I had low voltage to the coil.. Rpms shot up to 5000 on the first pull and was slowly still climbing. Dont like running that fast in the dark so i let out of it. :drink: