I壇 hate to be operating a 50 year old black smoke bellower but diesels can run pretty clean without that. My Grasshopper doesn稚 have any of the emissions crap on it and doesn稚 emit any noticeable exhaust. There痴 no black stain around where it comes out either. My M59 is also pre emissions and it blows a little puff on startup but isn稚 noticeable after that. I recently dug a water line inside a building. The door was open but the ventilation is pretty poor. There wasn稚 any noticeable diesel smoke when I got done. There痴 a 7.3 Ford in the building that I pulled out with the M59 because it would have smoked up the whole building in seconds.