In california, it is illegal to put a part that modifies a car's emission system from the stock system, unless it has been approved in a function applicable to your car. Each part that is "carb legal" has an executive order that establishes the application that the CARB has approved for.
Example:
I owned a 1989 Honda CRX DX. I had an AEM Cool Air Intake on it that WAS carb approved. I get pulled over by the cops, and get dinged for having a "modified" emissions system. I explain to the cop that it was a legal modification to my car, because it's "carb legal".
Well, the cop declares that the fact that the intake went down into the wheel well was an illegal modifaction, and that was the reason for the ticket. Well the kit was designed by AEM to either rest in the engine bay, or descend into the wheel well for "cold air".
I took the car to a CA smog ref, and he looks up the executive order for the intake I had in my car. Turns out the intake was absolutely legal, however, it was not approved for the application on my 1.5l motor. It was however approved for the 1.6l motor in all civic/crx si's. So basically I was screwed., and had to take it up the ass on a minor techinicality. I even went so far as to have a service station smog my car with the intake filter on prior to my appointment with the california smog ref. My car passed with flying colors.
Lesson learned: If you're going to modify your car with the intent to do so "legally", go to this web page,
http://www.arb.ca.gov/msprog/aftermkt/devices/amquery.php , and see if the CARB # on the device matches the make and model that it was legaly approved to be used on. If you choose to modify your car w/ non-carb parts, and ignore the laws, be prepared to take it up the ass from the po' po'.
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