I have a '06 901 w/ 200 Opti. The dealer put a 23p on mine too, but I exceeded the Rev Lmtr. I had them replace the 23p with a 25p. Better top end.
On Pat Goff's recommendation, I checked out PowerTech props and purchased a 24p 4-blade and a 25p 3-blade, both push the 901 in the high 60's GPS. Of course the 3-blade is a bit faster, but I find that 99% of the time I run the 4-blade, sacrificing 1 - 2 mph for the better hole shot and handling.
Talk with JR at www.pitstopmarine.com