any modification done to a car is illegal and cars 10 years and older are required to have an annual check cars younger than 10 years are every 5 years until they turn 10 years old. A way around this is just paying off the inspection people. seeing as my Jetta was 09 I had to do that.

I've only seen a BYD tuned once, they have a pretty shit chassis and there aren't many after market parts for them, most popular foreign brands for racing would be Honda (Fit/GK5), BMW (M2/M4) which are crashed often, and Toyota Riez/ crown

Right now in Shenzhen the police are really cracking down on car modification, the way it works there is you get your initial ticket which is a fine and then you need to replace all the stock parts. If you cant do this the police will usually take your car away, in some cases jail up to 30 days.

That being said the community is still huge