the thing tho is that from what I remember last I looked at my spare 96 oem cats sitting in my storage shed, they do not have any obd2 (or anything else) stampings at all.
so if kw's cat looks like oem and second O2 bung as required, all things being equal I doubt a smog shop will flag them.
OEM CATS did not have any markings on them. It is for "replacement" CATS manufacturers make. MagnaFlo decided to go through the CARB process and costs so they coud sell a CARB replacement. If the CATS in the car "look" stock I would bet the majority of the time there would be no issue.
It is when headers without air fittings or some other "visual" thing leads to a particular tech to look further
I passed with PCM tune, K&N CAI, headers, air pump delete, and (somewhat) obviously BRAND NEW Catco cats @ a STAR smog shop CA. I did however walk in to the shop with a folder full of info, including CARB/EO info printouts for all components (brought EO info for Magnaflow, better than nothing!).
I suspect your diligent paperwork, albiet you don't have the magnaFlo CATS, is what did it.
I don't volunteer any info but I do have CARB stickers on car for: Headers, CAI, MSD box and even RR (although they never see those). I don't say anything about the 383 or tune. Heck it even says "manual" under transmission on my printout of smog cert.
Obviously in Kings test he passed 'tailpipe" and had enough documentation for the tech to pass visual.
it is still fing BS as what comes out of the tail pipe is what matters. The rest is political revenue making BS....but if that is the game you just need to know how to play it...and win.