By all means do so. That engine can easily spin a 21p alum prop. I run a 19p SS prop and it does just fine. Truthfully I think I get better fuel economy with the higher pitch. There's plenty of horses available to spin it, so why not use them? :head:

i do have a 14.5x19 aluminium that came with the boat. the previous owner said the engine would only spin 5500 rpm or so whereas the 17p spins 5800 rpm or so. i dont think he really knew anything about over propping, he just wasnt that knowledgeable about boats. he just liked the rpm i think. what effect do you think the 19p would have versus the 17p on my performance and economy?

With 225 hp, I'm thinking you should be hitting at least 50mph - is that correct ?

Read some guys with 200hp Etec's and Merc Opti's are at 50mph +.
A few guys claim well over 40 mph with 150 hp.

I suppose a new Merc Opti 225 prop'd just right would push to the highest top speed.......... of the " legal " max horse power.

i have hit 54mph on the gps. calm windless freshwater lake conditions

Thanks for the input Ferm. It has been a great motor the five years that I have had it. It has only let me down once due to ethanol rotting away the diaphram in the fuel pump. Outside of that , she hasn't skipped a beat.