Used D-47's in an E-flite Tribute FX 3D. Very good servos. Had to make my own carbon 3D arms as the stock ones are really small for 3D work. I sold the plane after 200 flights and the guy I sold it too still has the plane flying and all servos still work. Pretty impressive. I've used lots of other brands and these are worth it. F3P flyers have routed 7.4v power directly to the servos and report increased speed. Maybe if you get a voltage reg it may help supplying 6v to them to increase speed. My .02