Car Customizing

Hi. I've been looking online for some legal info on car customizations (specifically for the state of Georgia). So far I have found nothing, and I was wondering if any of you could give me a little advice or point me to someplace that specifically discusses this topic.

For the most part I'm interested in knowing about the legalities of the various lights on the cars. I've heard a number of things: you can have extra lights as long as they don't flash; you're limited to the lights you already have; or it doesn't matter at all (aside from outright police or other emergency lights, of course). The only light related law I've ever heard of being enforced is the obligatory "failure to dim brights" laws (which isn't enforced enough around here).

Any help is much appreciated.