Like many, the lack of ankle tilt and his height (shorter than MP-10 OP, which many use this Megatron as the stand-in until MP 2.0 arrives) really bother me. And the 2 announced 3rd party addon aren't doing it for me either. So I've been thinking what I can do to improve this otherwise great figure.
Today I went into Marshall's (discount department store) and I found a Shockwave Construct-Bot and thought it might work.
The process didn't take long. There are peg holes on the side of Megatron's lower legs that's situated at a perfect location that the gray pieces (Construct-Bot Shockwave's arm Cannon) can peg into. The main operation is basically just cutout unwanted plastics on these 2 gray pieces so they fit snugged with Megatron lower legs. Then I cut a opening at the cannon's mouth (?) so the "ball-and-C-clip" parts can slot into, then attaching the feet to the ball joints. That's all the parts required to give this Megatron bulked-up lower legs and fully articulated feet extension.
You can see from the comparison shot that it's now about a head taller than MP-10 OP.