I didn't want to hijack the other intake thread with this question, but all of this discussion of CARB certifications being necessary for intakes to be street legal in California has left me wondering. How exactly does an air intake affect the emissions that a car produces? It doesn't seem to make sense to me.

 

Not sure yet about the cooper, in Atlanta my prev. Jeep 1999 had a computer the the emissions guy just pluged his computer into the jeep's computer and the Jeep told his computer I was ok and I drove off in less than 5 min., he did not shove anything up the exhaust or any thing, maybe I found a good emissions guy, I am hoping my April 03 MCS goes just as fast.

 

There should be no effect to emissions since you are basically just improving the airflow. The oxygen sensors tell the ECU to adjust to air density, etc.., and these sensors are after even the throttle body and also at the catalyst. My local MINI dealer said they are okay with both cold air intakes and cat-back exhaust, just don't modify any areas where there are sensors (like the header). (This is an oversimplification of course),. The CARB people are trying to protect our environment in California, but these rules are ridiculous.

 

I'm just speculating here, but it's possible that noise is a factor in this as well. If the stock airbox is considered a "sound dissipative device", then that could be a problem.. Intake "honk" can get quite severe without an airbox. In stead of setting a dB requirement for intakes, the EPA may just set a requirement for the manufacturer, and then for a vehicle to be compliant with regulations, it must have the OEM airbox installed.

Just a thought... I'm not sure if this is how it works or not.

 

I think it's just another one small way of the govt having some control over you so that in the end they could always have some say in deciding what should be legal and illegal. If your catalytic convertor isn't defective for some reason and the sensors are accurate, the intake cannot affect emissions in that manner.