[Aurornis]

> This mentions emission limits but does not require a catalytic converter

IIRC, technically if the vehicle meets emissions limits without a catalytic converter then it doesn't need one.

The emission limits are set such that a catalytic converter is required to meet them. They don't have to say "catalytic converter required" but the targets are chosen so that a catalytic converter can reasonably achieve them.

If the laws simply said "catalytic converter required" then manufacturers could put a tiny little square of catalyst in the exhaust and call it a day. Formula 1 isn't the only place where rules have to be written explicitly to avoid clever workarounds.

[mulmen]

> Catalytic converters were required

You claimed they were required by law, but they weren’t. Now you claim they had them anyway, but I can find no evidence of that either. Do you have some evidence that 1988 GMC 6000 trucks had a catalytic converter from the factory? I can find nothing online to support that claim.