They are clearly not as bright as HID but with this bulb they are meant to be used as fog lights in rain/snow conditions and not as driving lamps. HID fog lights are not very efficient in snowy conditions as they reflect too much light back to you.
I had HID 4300K fog lights in my previous S4 and they were clearly brighter.

Cost is $35 huge difference with HID and a lot less trouble to fit (2 minutes litterally).
I bought them on e-bay from a seller in California called LCFT. Top notch seller (I bought 3 other pairs later for my other cars and for a friend)

 

Thanks for the feedback. I think I'll try a pair (also saw them on eBay for $30-35). For that kinda money no big deal if they are not something I stick with forever. And yes, way easier to install too.

 

looks awesome.. what was the cost if you dont mind sharing?

 

I think 5000k looks good and doesn't compromise too much light output