A very interesting piece of the X-Factor is the start of the downswing. On the backswing the shoulders far out-turn the lower body, maybe 30 to 40 degrees more turn. Now when we start down something really interesting happens.
X-Factor: Lower Body Swing Power
The lower body starts and actually increases your X-Factor. That the differential between your hips and shoulders. From the top you might start a little practice move where you can feel the lower body move. You might feel your shoulders stay back as the lower body starts down. That is one way to feel it.
Move Your Knee Towards the Target
Another way is to feel that left knee move first towards the target. What you don't want to do is go up to the top and then start the shoulders and hips down together. Worse than that start the upper body ahead of the hips. Terrible move.