I had always though about extending my outside leg but taking my CSCF coach 2 had made me realize that there is a better approach.
The new line in racing involves going straighter toward the gate and then applying an impulse late in the turn to achieve direction and power. Turns are no longer C-shaped, rather they are J-shaped. To be able to ski such a line, there needs to be adequate power applied during that impulse to allow the skis to bite under all that momentum built up from travelling down the fall line.
The answer is the use of hips to bring your centre of mass inside the arc. Pushing on the outside ski and attempting to straighten the outside leg is acceptable with the C line but you have not felt skis grip until you have activated your hip.
In order to activate the hips, it is necessary to have a narrower stance and good separation (keeping upper body facing down the fall line). If separation is not there, the hips will be engaged at the beginning of the turn but not at the end, resulting in alot of inside ski wipe-outs.
The progression I underwent to get the hips working was by skiing two straight days with my legs completely glued together, using no joints other than hips, ensuring that I focused on separation. I did this both freesking and in gates. My goal was to attempt to get the hip to touch the snow inside the arc, and if I wasn't wiping out I wasn't going far enough. After that, I spent 3 or 4 runs doing the boot touch excercise (ouside hand reaches toward outside boot) to recenter my weight at initiation. Then I was off.
Once you get the feeling, you will see that your vertical movement will use hip joints, as well as ankles and knees, and your outside leg will be straight as a consequence. By using hips for the bulk of your vertical movement, it's very easy to get low and achieve high edge angles.
Let me know if there's anything unclear and I can try and help you understand, but check out that Blardone GS video again and see if you understand what I mean.
Take home message: brings the hips in rather than extending the legs out.