Has anyone used this site before? I purchased the Chevy Cobalt LED Kit which includes a dome light, trunk light, and license plate light that come in many colors. They have HID headlights but I'm not sure what I need to make sure they work... Do I want my "bulb size" to be Halogen Hi or BiXenon, and what is the difference? And, do I need the HID relay? The link is here but you may have to enter car information (i.e. Chevrolet > Cobalt > 2010). Thanks!