I amnot sure about the HID syatems on the Viper (I am planning on this upgrade, but I haven't did it yet). But I will definately agree with the Philips HID system. I purchased a Philips system for my motorcycle this spring...and this is DEFINATELY the best money I have ever spent on my bike. For the first time I can see the road, the sides of the road, and my bike vision is absolutely wonderful. I shopped around until I found this site, and they are great, great service, great prices, and top quality merchandise:
http://www.xenonking.com/
The 4300K will give you the whitest, brightest light you can get. I highly recommend them!
