Currently BAR & CARB look after vehicle pollution requirements and enforcement and for consumer vehicles post 79 and older than 8 model years where the target cars require biennial smog check. The following website states:
In order to receive a valid smog certificate, your vehicle must pass all parts of the smog check inspection. A smog check may include any of the following tests:
- Visual inspection of emission control components and systems.
- Functional inspection of the vehicle's check engine light, ignition timing, exhaust gas recirculation system, fuel evaporative system, and gas cap.
- Functional inspection of the vehicle's onboard diagnostic (OBD) system.
- Tailpipe emissions inspection, or emissions test.
https://www.samsara.com/guides/the-complete-guide-to-california-smog-check-requirements/
Supposedly it can be a big PITA
Worse still, it’s getting even tougher in California where the authorities have gone after performance/mod shops for knowingly selling non compliant stuff that get put on road cars by their owners. Some businesses have been fined and gotten customer lists seized
Such was mentioned in a performance shops YouTube video I saw a while ago (sorry can’t find it).
And it’s not just California as Utah also gets into such action
https://kutv.com/news/local/diesel-brothers-ordered-to-pay-1m-in-pollution-case#
No doubt at some stage the same sort of actions may start to occur down under and it will all feel rather heavy handed for the old timers. Until then, people will think they can do what they want with impunity but the reality is to do anything non factory requires either full certification by the owner or using components that come with certification from the seller.
Luckily enforcement here isn’t gestapo strict as yet but if they want to strictly apply current laws many will be screwed and fined heavily
The future will be welcome to the world of EV modding