I've got white LEDs on a Fiero that I bought for my wife a few months ago. The previous owner installed them along with HID headlights, a fancy alarm system and a bunch of high end stereo stuff. All these extras are worth more than the car!

 

We've got the oznium inferno led kit under mitzkity. According to the local police, and confirmed via search, underbody lighting of any color is technically not illegal in CA as long as the bulbs/light emmitters are not visable. However, that doesn't keep a cop from pulling you over and giving you a ticket regardless. Just means you can fight it.l

 

varad.com has awesome product i have a underbody from them