I'd argue they are industrial safety-critical equipment.
> In the mean time, see if you can legally make any changes to your car's catalytic converter and replace it with a pipe.
Nobody goes after Subaru when people run catless. This is a silly strawman.
Exactly - the government doesn't go after Subaru when people remove their catalytic converter because the car isn't industrial equipment. The EPA does go after tractor manufacturers and distributors when it is possible to modify a tractor to remove its diesel particulate filters and similar.
https://www.epa.gov/enforcement/tractor-supply-company-inc-s...
> According to the charges, the company's engine software controls the timing of fuel injection into the combustion chamber, causing the engine to emit excessive amounts of NOx while the truck is running on the open road. However, the company's engine software is designed in such a way so that these emission levels do not show up on the federal test.
What do any of these have to do with end users modifying their equipment?
If tractors were able to be classified as cars for warranty and such - such that the people who make modifications to them are liable for damages caused by the device (rather than the manufacturer), there wouldn't be as much of an issue.
As it is, if you are able to modify the emissions controls for a tractor and the manufacturer doesn't try to make it impossible to do that, the EPA goes after the manufacturer instead of the owner or operator.
In the mean time, see if you can legally make any changes to your car's catalytic converter and replace it with a pipe.