Actually, in many countries, even the US, it is illegal to modiffy cars. In California, law enforcement agencies are only starting to be a bit strict in enforcment with respect to car mods. But yes, the rules are there to confiscate items (maybe not the car..well maybe impounding the car). You can check up at the DMV website, and you can find a myriad of anti-modification laws. Just be friendly to your local CHP guy when he stops you

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