^^^^^all of that is true, and I never have seen a smog test tech crawl under a car to visually check a catalytic converter to see if it was an approved one. But they COULD.

I looked pretty carefully on the DMY smog site, and couldn't find any answers about this.

In addition to the visual inspection, they usually look to see if the equipment looks like it was tampered with, and then of course, the test is performed to get the emissions readings.

Maybe you could call a "test only" station and ask them the question. It is a good one. The smog site mentions that the state does NOT control what fees the "test only" stations charge, though, so you need to find out

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)