I question the comment about Europeans drilling holes in their DPF to effectively eliminate it because my experience living in multiple West European countries is they do not allow anything like this under penalty of a major fine or if intentional, possible prison time. I had to have my car inspected yearly at a certified station. It was a several hour serious check. Any suspicion of an oil leak takes your car off the road as one example. Emissions items all checked and properly working. They are much more serious about well tuned vehicles than the USA - based on living in 3 West European countries and 4 USA states.