This weekend, I replaced my stock fog lamps as they were pitted like crazy. I found a pair of new Depo's on eBay for a little over $100. To prevent this pitting from happening again I went with Lamni-x and got a some film with a slight tint on it. I wet applied the Lamni-x with "Rapid Tac" which is a great spray to use for vinyl or other wet applications. It made it some much easier to align the Lamni-x as it only cover the visiable part of the fog lamp when the cover/grill is back over it.
While I was working on my fog lamps I updated to 3000k HID's. I do miss my retrofit projected fog I had in my B5 S4 as they was zero glare with them. As my current B8.5 S4 is using a reflective housing, glare is a problem. Typically what I will do is measure from the ground to the top of the fog lamp and then put a line of tape on my garage door at the same height (showing below). I try to get the hot spot of the beam to be slightly below the line to minimize glare as the beam is angled down.
I do recommend that if you want HID's in your fogs, it's best to turn off the "corning light" function in VCDS (VagCom) or OBDEleven. The corning light will turn on the fog light for which ever side you are turning too at low speeds like in a parking lot for example. This is just not good for HID as you don't want to turn them on and off in short intervals. Plus there is a warm up period of HID bulbs, a quick on and off is just damaging them.
So far I'm pretty happy with the setup. The fogs are slightly less noticeable when off, but when they are on, the light is perfect for our often rainy Seattle roads. I'm be looking for a different setup of HID bulbs as the color is a warm yellow, but not the golden yellow I am after. We will see...