To "delete" or not to "delete"

The "catalytic converter" on a diesel that you are referring to is the "two way" or DOC(Diesel Oxidation Catalyst). The DOC is not and does not do the same function as the SCR(Selective Catalytic Reduction) system that requires DEF or the NAC(NOx Adsorption Catalyst) that removes NOx. The DOC's job is to reduce carbon monoxide and hydrocarbon emissions and are still being utilised on diesels today. So yes, the "catalyst" on the pre DEF engine was useless at reducing NOx since that was not it's job. It is the EGR (which you removed your in cylinder EGR) that has the job of reducing NOx by lowering combustion temps.

You are starting to sound like 6.6 Oilburner in making assumptions of how you think these systems operate.

Pot callin kettle black?... you talk the talk... a "2-way" cat does remove some of the NOx... and I said "some" until the 3-way cat was introduced which removed more NOx albeit only by some 8-9%. So... who's making the assumptions here? New diesel engines in OTR vehicles are still putting out as much nitrogen oxides now as they did 15 yrs ago!

Shut down all industries that use fossil fuels to produce their products, then get all those homes that burn fuel oil to heat their homes to stop (can't use firewood or coal as they also contribute nitrogen oxides) shut down all trains, planes and automobiles... all contributors... there ya go Shinner some worth standing on yer soapbox about... but then your as dirty as the rest of us! :B

The ULSD only reduces SOX formation. Oxides of sulfur result from burning, you guessed it, sulfur. SOX can't be converted to anything safer so the only way to control it is limiting sulfur in the fuel.

Sulphur is used in fertilizers, Shinner would have us not use it either, as Sulphur breaks down and mixes with the available Oxygen then we get all those nasty pollutants.

So now we have no means to process, grow food, or transport goods, are freezing to death, unable to cook our favorite steaks. Carbon dioxides are reduced to a point that all vegetation starts dyeing off and mother earth turns to dust... :E