If you're worried about cops, don't mod the car. They can find anything they want to pin onto you if they wanted to, but it's all about how you carry yourself. I used to daily drive a 2JZ 240sx full roll cage 5 inch turbo back and all but I carried myself properly on the streets and never once got harasses.
I doubt many ppl have got the headers already, I think they are just now being released to the dealers to push to the public but in small quantities... check in with some of the forum dealers (maybe 86speedfact I think they said they are getting 10 headers).
As far as regulations/smog goes well... you're in cali. You're either stock and legal or modified and illegal. Whether you throw a catback on, or completely overhaul the engine internals forged rods cams pistons and throw a turbo kit on it doesn't matter, either or is just as illegal.
Hope that clears things up. The short end of it is simple... It's your car, it's your life, it's your money... Do as you please and do what makes you happy don't worry about the one or two times you might get pulled over because whatever happens happens man just enjoy the ride.