I have wondered this with some JD's. Not deleting emissions persay, but running more preferred emissions. In 2015 JD added a DPF to their 3 cylinder 5E series. (I own a 5075E, so I don't want to speak on what or when they added any given emission systems to any other given machines, as I don't know for certain, even if I have a good idea as to the correct answers) In 2023 JD changed the 3 cylinder 5E from using a DPF to using a DOC like MF and a few others sometimes use. I believe a DOC works more like a catalytic converter which just naturally gets really hot, and burns up carbon emissions as opposed to trapping the emissions and using fuel to ignite the trapped emissions in the canister once it fills to a certain level, i.e. what's referred to as a regen cycle. I'm sure the computers would not be happy trying to switch one over to the other. I'd much rather use a catalytic converter than a diesel particulate filter if I had to choose one evil over the other.