I've been flying the 68" ExtremeFlight Yak with a Hacker C50 12XL using a 20 x 13 APCE prop and TP10S3P 6000 Lite LiPos (two 5S3P packs in series). Performance is spectacular. I've yet to exceed 2/3 throttle and can climb vertically out of sight. I use around 4400 MA in a 9.5 minute flight flying AMA Masters maneuvers. The Hacker turns just about 6000 RPM at WOT. I use the Hacker Acro90 ESC and a combination of Futaba and Hitec digital servos.

Mike M