I don't know for sure, but the EPA can't enforce emissions on private property correct?
Yes they can and do. Just look at lawn mowers, generators and power sports.
Additionally they own a fleet of drones to spy on farmers and ranchers and hit them with fines.
Side By Sides all come with cats and in California I know a Can Am will have an air pump as well.
Maybe you are confusing the EPA with the DOT?