I currently live in CA and want to switch to a cold air intake. But no matter what the brand it seems that they are all "illegal" for use. For those of you that live in a similar state with emission control standards and have upgraded, what are your thoughts?
I did mine! I live in CA. Just put back the stock when you are due for smog.
Starting January 1, 2019, if your vehicle is less than 4 model years old, you can pay a smog abatement fee instead of getting a smog inspection for the first 8 years that your vehicle is registered. — DMV site —
The intakes are really easy to swap back come inspection time. Took mine out to adjust the headlights, was quite impressed with how easy it is (takes about 15 minutes, and you just need a basic socket wrench).
I ran a Fiesta ST with nearly every bolt-on in Cali for quite a while. As mentioned, you've got years before you need to do your first inspection, so the main thing is just don't do anything to get yourself sent to a referee (don't straight pipe your car, for example).