I have read around about questions concerning HID headlights

I came upon people saying that there are some HID lights are legal if they DOT approved. Also other saying that if it is not provided by the manufacturer then it is illegal.

So my question is, is it legal to install HID lights on my 2000 Mercedes CLK 320.
Xenon high intensity discharge headlights is an available option from the manufacturer for my year and model as listed on edmunds.com.
Also what would be a good level of intensity 5k, 6k, 8k, 10k, 12k?

Thanks in advance

100% legal as long as the lamps you purchase are labeled DOT Approved or are from a DOT Approved Aftermarket distributor/parts shop.

As far as intensity...doesn't need to be much...find what works for you.