There's more to it than emissions and air quality. I think it has more to do with tampering with the stock system and having to be approved by the California Air Resources Board and paying those fee's. I'm sure the high flow intakes contribute to some pollution but it really can't be too much if CARB is approving the designs.
Here's my Cosworth...Well worth the effort to find a used one for me in California!
Autolite 103's, Cosworth CAI, FRPP Suspension, Strut Bars, DIY Short Shifter, SVT Air Dam, BSD, Poly Trans Mount, Borla 2.5", Roush Wheels, Tune...