Because of the Glare that most kits put out on Halogen Headlights. I wouldn't worry too much bout it, just reaim your headlights after your install and have one of your friend's get in a car in front of you goin in the same direction and one goin the opposite way to see how much of a glare you have. You got a pic of the kit or at least a description of what came with it so that we can help you install better?