R Forum (2004-2007)
https://www.roadandtrack.com/car-culture/a37262122/what-californias-new-ecu-law-means-for-tuned-cars/
As of July 2021, smog tests in CA began including a check for modified ECU software. I'm not sure how it is elsewhere but in CA, OBD-II cars no longer get the sniffer test, so it's based...