Hey Core, good to see you again
Yup, that law is already passed and regularly enforced here. Passed 3 years ago if I am correct.
Nobody will forget when the cops turned up at our little Tianma circuit to raid all the car modification shops two years ago. Scrutinizing paper work, licenses to modify DOT vehicles (which does not exist lolll), business registrations and all kind of other checks. Hard bully stuff!
Nearly all of the shops who were not in-line with this unpopular regulation had their toolboxes and equipment confiscated, some shop owners given fines (small, but regardless). Bit of an advanced warning if you'd like. Wasn't pretty (cop cars and trucks at the race track)
The only dudes that were left alone was the motorcycle shops for some strange reason
Somehow the sale of performance related car parts and modifications is still strong but rumors are they'll soon crack down of the vendors of those, warning have already been issued to some (I heard, unverified). When exactly that nobody knows so inventories are kinda limited on those here.
They did made it illegal to import car parts however (already enforced). You need to be licensed to import anything car related here. If the customs reads "car parts" on a parcel/import, you bet you'll receive a pick-up card in your front door. The only guy who can get your imported parts out of the post office is Porsche (or Mazda, Honda, GM) lol
But then, this is China. They bloody well do what they want here. Sure will be a tad harder to enforce in the USA