Technically if ANY of the light from the tubes is visible, meaning even if they just make the ground glow, and they do not meet CVC and DOT code they are illegal. Blue or red are EXTRA bad, you can get a ticket for illegal display of emergency colors which if I'm not mistaken if over $1000 ticket. It's not worth it. If you have an all out show car and you want to show your stuff off at a show it's cool. Otherwise stay away from it. A friend of mine got pulled over because he had neon tubes in his back deck and they were visible from outside of the car, the cop was nice and gave him a warning because he really thought as long as they were inside the car and they weren't directly visible it was ok, but it's not.

Neon tubes that are are on while driving down the street are "Ricearoni that san fancisco treat. ding ding"