The warning is automatic and comes with literally every product like this because of the '66 and later emissions control devices. The companies don't want any govt entity coming after them saying they're purposely defeating emissions standards.
They don't know where you are, or care. It comes in the box and online. In your case, yes Summit likely already knew you were in CA, but they don't care either. It's probably easier to just show it to everyone instead of just those with shipping addresses in CA.
It's not just CA residents that have to know that stuff anyway. Goes for a lot of different states.
If you don't remove or modify the existing smog control devices, you're good to go.
Even headers are almost legal if you don't modify your smog stuff. But not "legal" unless they have a certificate saying they've been approved.
Adding EFI may or may not be an automatic visual fail, but it would be in this case because it's also a 4bbl where no four barrel carb was ever available on a Bronco.
So like said, unless you get pulled over and spot tested for some reason, since you don't have to get it tested normally, you won't have an issue.
And besides, even if you did it's easy enough to swap back to a carburetor to test, then go back to EFI when done.
Bit of a hassle of course, but not the end of the world either.
Paul
