2003 tracker pro 165 prop help

[arrowslinger#1]

Picked up a 2003 tracker 165 with a 40hp 2 cylinder 2 stroke
it has an 10.88x11 pitch prop now - over half throttle gets me in the rev limiter
what comes factory on this boat ? I can run around 25 (dash speedo) backed off the rev limiter
Looking at a black max maybe a 14 or 15 pitch????
any help would be greatly appreciated
thanks!
Ratio =2:1

 

[AirForce]

Have you tried Mercury's prop calculator? http://www.mercurymarine.com/propellers/prop-selector/#

 

[arrowslinger#1]

Yes it shows a 14,15,or16
Trying to narrow it down