I know for headers and intake manifolds, and even intakes need stickers to pass inspection. What about the fuel rail and throttle body. will it pass smog in California??

 

Call the smog place and ask.

 

The stock rail flows enough for good power as it is, so I'm not sure why you're worrying about that. You can upgrade to a larger OEM throttle body, as well...but there's no gains to be seen without tuning, and AFAIK there are no real tuning options to you cali people.

That said, call your local smog station and find out.

 

not it does not on the smogcheck.ca.gov site answer is no

 

fuel rail might not pass visual. But it won't affect numbers
Throttle body has potential to mess with the air fuel ratio, so I don't know.