99-04 Mustang Headlight Install and Comparison It is a known fact that 99-04 Mustang headlights fade and begin to look pretty ugly. If you have been thinking about replacing your 99-04 Mustang headlights, we did some of the leg work for you. We took the 4 most popular headlight kits we offer and installed them for a comparison. To further help you we walked you through the extremely easy install for the headlights. Check out the blog and let me know what you think.