Hey inspector! Good info. Nice to have a knowledgeable source on the chemistry and workings of the inspection system helping. My theory is pretty simple: Whatever I drive, be it city car or huge SUV, I want it to be as efficient as possible (probably the German in me). I tend to set up my cars for good fuel mileage. Usually just one notch rich if adjustable. That way the NOX is kept down and I let the cat eat the HC. I had a '77 Suburban (tow beast) with small block 400, Quadrajunk carburetor, headers and dual exhaust with NO cats. (Legal for '77 HD emissions). Came in with a 122 HC and all others in spec also. Fellow at the testing station could not believe it. Simple really. Low miles engine (60k). Good state of tune. I was able to tease a couple of MPG out of the truck by keeping it in top shape and on that truck, that's a big percentage!
Nowadays with closed-loop systems, it's just too easy. Now if we could just get the automakers to distribute all the OBDII codes. Then we could all get our cars running right with out paying thru the nose.