HID Headlamps - Bright Enough??

You have a few possibilities here. Most factory HID lights are rated around 4300K which is close to daytime light and should also be the brightest in terms of lumen output.

I haven't seen a stock Ford HID setup so I can't comment on your particular question but, I have seen a Saleen HID and I had same thought. I noticed that the the light was very bluish.

This either meant that the car had the correct 4300K lighting and that the housings are just cut in a way that when they scatter the light is very low (not to blind people) and focused thus limiting your vision making them appear more blue then they should have been. Alternatively the car may have had higher temperature bulbs which are blue and have a lower lumen output and are thus dimmer.