I came across one of those guys who MacGyvers their vehicles to emit extra exhaust

[Xithras]

61. Even relatively new diesels do.

This is one of the reasons why so many of those hyper-mileage European diesels that get 70+MPG can't legally be sold in the U.S. Brand new diesel engines should never smoke, but it only takes 2-3 years of cheap fuel and poor maintenance for a diesel injector to get dirty enough to start smoking on acceleration. Diesel engines are DIRTY, and their "smog test" is much simpler than those used by gas burning cars. Unlike gas burners, diesels don't actually get their tailpipe emissions measured...it's simply a test to verify that the original smog equipment is still there and that there isn't any smoke. A bottle of injector cleaner a week before the inspection will usually clean a newer one up enough to pass, but the fix doesn't last long.

I'm not saying that the guy didn't modify it, but the smoke on acceleration sounds more like poor maintenance. We've got a bunch of these "Coal Rollers" jagoffs around where I live, and they generally just smoke constantly when the driver flips a switch. Big billowing clouds of black smoke as they cruise down the road or idle at stoplights. Smoke on acceleration usually just means crappy maintenance.

You don't see it on most diesel pickups because NORMAL (non-a**hole) diesel owners see black smoke on acceleration and think "Hey, I need to go get a tuneup", and not "Great, I get to go annoy a liberal". Like so many other things in America, the Teapublicans have figured out a way to take a bad thing and make it even worse.