For those that are into that sort of thing, they can and will modify any diesel. Which EPA regs they meet is irrelevant.
However, at least in the part of Canada that I live, I hardly ever see any modified diesels, and the one that are, are mostly pick ups. People buy them for fuel economy gains over similarly sized gas engines and not to roll coal or "stick it" to the greenies.
IMO, but EPA has outlives its usefulness for a long, long time now. They should be relegated to simple monitoring and compliance of the manufacturers with existing limits and not setting new ones.
What they do now has no relation to protecting the environment, but extracting as much money as they can.