I live in a bubble, oops, I mean San Francisco... SF is never a problem for me because well, my car isn't that modded and anyway the cops have better things to do, right? But of the greater Bay Area region, I must say that some suburbs can be hell for modded cars. Fremont is fairly notorious, at least they used to be. They would pull over cars for dumb stuff like no front license plate, and then you would see hoods being popped. I don't know if other states have referee's, but California does and if you ever get sent there, you better hope that your mods are super easy to reverse.
My good friend has an F80 M3. Yas Marina Blue, competition package. It doesn't help that the car is already flashy, and on top of that he's rolling on Championship White BBS FI-R.. but he has no front plate. I mean, you're not going to drill your expensive bumper for that right? Anyway, motorcycle cops (traffic cops) will be trained on him every single time as he passes with no front plate, but as he passes they see that he has dealer papers on the rear, so they let him go. Maybe they are just looking at the nice car? Mind you this is in a residential neighborhood in a suburb where the police don't really have much else to do.
Also, not driving like a complete douce helps as well. (I know I spelled it wrong, but I like doing that sometimes, for fun.) Lots of modded cars have drivers that drive like douces, so that doesn't help any of us either.