claytucker,

You may be accustomed to quicker 3D flight than those of us using a 13x5 or 13x4 on a OS FX .61. I find that I a larger diameter, lower-pitched prop gives me better "plane response" as opposed to throttle response. When I've used a 12x6 or 12x8 as the manufacturer recommended I experienced an elastic band effect when initiating or maintaining a hover, whereas the 13 MAS series provided the neccessary torque to pull the plane through any maneuver. I don't fly my T _ _ _ T much beyond 5-15mph through most of a flight and rarely (if ever) above 25mph. The type of 3D flying I do seldom has the wings producing lift, so my sweet .61 carries my plane for most of a flight. Hope this is of some help. Consider temperature and humidity as well when you're considering a prop change. I'm in the cool/cold upper midwest and that makes a difference.

Peace,

Downtrodden