More information: What I was recalling is the EPA's Engine Switching Fact Sheet from 1991. https://www.epa.gov/sites/default/files/documents/engswitch_0.pdf h

More information: What I was recalling is the EPA's Engine Switching Fact Sheet from 1991. https://www.epa.gov/sites/default/files/documents/engswitch_0.pdf https://www.epa.gov/sites/default/files/documents/engswitch_... I learned today that it was replaced in 2020 by the EPA Tampering Policy. This one doesn't seem to focus so much on engine swaps but on the emissions devices themselves. https://www.epa.gov/sites/default/files/2020-12/documents/epatamperingpolicy-enforcementpolicyonvehicleandenginetampering.pdf https://www.epa.gov/sites/default/files/2020-12/documents/ep...