What exactly seperates legal upgrades from illegal upgrades? I mean I know about exhaust noise levels but what about headers, intakes, etc.? Under what law is an intake illegal? For what reason? I always thought that if your car could pass emisions then it was ok. What are the limitations? Bare with me here, I have limited info on upgrades besides what I read on forums! Any info is appreciated.

 

SMOG....it is all about smog regulations. California sucks. Check local laws before buying parts.

 

Last time I was lost in Newark I remember seeing the emission testing stations, so I think you would also have to follow the same guidelines as in California emission testings..

Each state has vehicle inspection laws, but also consider law enforcement guidelines as well.. tinted windows, license plate covers, bulb colors, etc,etc..
I have even heard a cop say a person could be ticketed for those illuminated washer nozzles on the hood..silly huh?

 

In Cali, I believe you have to have a CARB # on the item you modify.

Like AEM CAI's as well as DC headers have CARB numbers on them to legalize it.