There's a reason cars have amber marker lights in the front, and red ones in the rear. It's so you can tell at a distance which direction a vehicle is traveling in. This is far more important out in the middle of nowhere than in an urban setting, but there is a rhyme and reason behind the codes that apply to vehicle lighting.
I can think of about 10,000 different ways you can customize a vehicle that don't involve fucking with the safety related items.
I've never been able to comprehend the obsession with screwing vehicle lighting...