I work in the DPF industry - and given the relative "newness" of these systems, I don't think anyone is an expert yet (even though we've shipped over 12,000 systems worldwide). So, I just thought i'd add a few thoughts - which is dangerous because everyone has their own experience and at least two opinions 
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Depending on year, your engine is registered with the EPA - (https://www.epa.gov/sites/production/files/2020-01/nonroad-compression-ignition-2011-present.xlsx) this link is an excel spreadsheet for each approved engine after 2010. It'll show the type of emission controls (albeit in EPA speak!). A few points: DPF's trap particulate matter (PM). PM is unburned fuel. The hotter the burn, the less PM produced. High engine RPM doesn't necessarily mean high temp combustion. High engine load, usually does mean high temp combustion. There are engines that never get to high enough temps in certain applications (Transport refrigeration Units - TRU's with Kubotoa 2.2L engines never get to temp), so there are two types of DPF's deployed out there - ADPF (A is for active meaning there is a secondary source of heat to increase temp - mostly by a fuel burner, although electrically regenerated systems also exist) and PDPF - P is for passive, meaning the Engine needs to produce enough heat on its own. The DOC (in non-SCR systems) is there to convert other gasses, but as a side product they increase the oxygen, which lowers the "light off temp" of the DPF (the temp at which a regeneration occurs). So DOC's are a net benefit in most cases. Engines are looking at back pressure (and / or time) to determine when a regen should occur.
While I work with people at the top of the industry technically, in my opinion, no one is an expert yet. Way too many variables to arm chair quarter back these things.
.... Depending on year, your engine is registered with the EPA - (https://www.epa.gov/sites/production/files/2020-01/nonroad-compression-ignition-2011-present.xlsx) this link is an excel spreadsheet for each approved engine after 2010. It'll show the type of emission controls (albeit in EPA speak!). A few points: DPF's trap particulate matter (PM). PM is unburned fuel. The hotter the burn, the less PM produced. High engine RPM doesn't necessarily mean high temp combustion. High engine load, usually does mean high temp combustion. There are engines that never get to high enough temps in certain applications (Transport refrigeration Units - TRU's with Kubotoa 2.2L engines never get to temp), so there are two types of DPF's deployed out there - ADPF (A is for active meaning there is a secondary source of heat to increase temp - mostly by a fuel burner, although electrically regenerated systems also exist) and PDPF - P is for passive, meaning the Engine needs to produce enough heat on its own. The DOC (in non-SCR systems) is there to convert other gasses, but as a side product they increase the oxygen, which lowers the "light off temp" of the DPF (the temp at which a regeneration occurs). So DOC's are a net benefit in most cases. Engines are looking at back pressure (and / or time) to determine when a regen should occur.
While I work with people at the top of the industry technically, in my opinion, no one is an expert yet
. Way too many variables to arm chair quarter back these things.
