Boosting horsepower on a 2003 9.9 h.p. 4 stroke long shaft outboard

[TundraDan]

I am looking for advise and info. on increasing the h.p. on my Yamaha 9.9 hp. 4 stroke outboard. is it possible, economical or even wise? also advantages or disadvantages of higher pitch prop.

 

[tpenfield]

It would be called getting a 15 hp or even a 20 hp. I don't think it is worth messing with a small engine just to gain a couple of hp