Pro

So the product makers claim that the product is smog legal.
What if you put more than one smog legal product at once on a vehicle? (Like I have done to my truck).

Example - "smog legal" headers, cats, mufflers, chips, supercharger, etc. Well, having one of these items on might be smog legal, but what about having them ALL on at once?

Adding headers increases air flow, therefore more exhaust, correct? If so, then maybe it just increases it enough to where it is smog legal with the existing mufflers and cats. Well... what if you replace everything else behind it? (That is so called smog legal).

aklim

AFAIK, smog legal (with an EO number) means that it does not negatively affect the emmissions in the exhaust.