Question on what size prop should I use
 

I have a 1989 Baja 250 Sport that has a Mag 454 with a Bravo One, 1.5 ratio. I have a 21 pitch prop 3 blade Mirage on it now and it is to small. I have a chance to get a very good and slightly used Mirage 25P 3 blade for a nice price. I think a 23P would be the best, but I do not have the time to look for a good used one and I am on a budget after spending $11,000 on the new engine and some other work. Will the 25P Mirage work or am I just wasting my money?

What RPM and speed are you running with the 21? When you go up from a 21 to 25 you will drop about 600-700 rpm. If you are turning 5600 rpm with the 21 then you might be able to go to a 25. 23 Mirage plus will drop about 300 rpm, so if you are turning the 21 about 5200, the 23 would put you at about 4800 to 4900, which is a good range for a 454 mag.

25 will be too big with your power. A 23 Mirage Plus will be the best prop.

i am running a 23 on my 250 right now, it gets up on plain better than my buddy with a heavy 28' maria with a bavo 3, it ticks him off lol. im running around 450hp but the stock 330hp used this prop, i am jumping to a 25 as soon as i get my motor more tuned out.