Thankyou Matt;

Yes the speed 400 with at 11.1 v don't live quite long, but I need to give them that power, because I live at 2400 mts above sea level, thats about 7920 ft, and fly at nearly 3000 mts. I've tried with 2 cell Lipo, without good results. Never theless, I've flown witha speed 400@ 7.2v and 3 cell LiPo, arround 20 without any problem.

Maybe with a speed 600 direct drive jumping to 2100 Mah, what prop would you recomend me with that motor.