I just purchased  a 9.9 yamaha its an 2006 an the owner told me to get an stanless steal prop for better take off.Is this true?? If so does anyone have a clue which one to get because I just get the runaround from some of the dealers.

If you added about 100 more horse power, a stainless prop with more cup may be of benefit. There is not much "take off" with an engine that small. If you are having problems with low rpms, get a prop with lesser pitch.

I have a 2005 yamaha 9.9 4s.  I run a piranha prop and I am very happy with it.  They are composite props.  

http://www.piranha.com/

Thanks for the web site.I'll give a look

I just went through the same dilemma recently.  After all my research I replaced the prop on my 9.9 Evinrude with another original factory prop.  

I remember reading that the whole SS vs. Aluminum flex issue is not a factor and the article was pretty convincing.  It stated that the reason Alum. is inferior to SS is not due to flex, blade edge thickness in alum. plays a larger role.  As far as a 9.9 if you want a quicker hole shot go with a 4 blade, more top end go 3 blade.  Save your money though and go aluminum. Michigan Prop and Solas are great aftermarket props, you should be able to find a great deal on Ebay.

 Put a set of Boysen reeds in it! you'll be happy then