So it must be a California thing. They don’t check serial numbers here (Texas). They just stick a probe in the tailpipe and you either pass or you don’t.
I'm envious!
Back in the olden days when you had to only smog your vehicle on change of owner, I knew a guy who would pull the probe out until the exhaust was diluted enough to pass. Now they can tell when you try that trick plus I believe it's now a $10k fine.
I'm glad I'm no longer a mechanic.