I too would love to see some lab testing. The data from Dark Iron Diesel is probably sufficient for fuel economy and my own personal anecdotal data on deleting the EGR confirms in my mind the damage done to the engine oil and thereby the engine from additional friction is quite noticeable. With the EGR my engine oil is black before 3k miles. Without it the viscosity and color are dramatically different. I suppose I could send oil samples off to a lab but it would just confirm what I can visually see. I also had to rebuild my engine at 250k miles. I am curious to see how many more miles I can get without the EGR.

You know, what auto manufacturers spend a lot of time and money doing.

I do not believe I would trust anything coming from manufacturers. They have a serious vested interest in people using more fuel, adding corrosive materials to their oil, burning up engines and buying new vehicles. The oil industry would also love to see people using 30%+ more fuel and having to change their engine oil on a very regular basis to compensate for the damaging highly abrasive exhaust being blown back into the crank case.

I think it might be a challenge to get some empirical data for the other numbers on diesel engines as the locations that have smog checks and bi-annual testing will not have many people deleting their emissions systems. Conversely locations that do not test such as my state will not have the necessary smog testing equipment to get accurate numbers. I think the best we can get is the limited smog data from the ECU unless someone wants to take their offroad racing truck to a smog center but I suspect those numbers will be off due to racing specific tuning.

As for dumping more toxins in the environment I don't think it's super simple to break this down. The smog systems on diesels are just breaking up the particles to make them smaller but at the same time dramatically increasing fuel consumption. I don't like the particles being made smaller. Sure, less irritation to the throat but now those particles can get past the defenses in my lungs and get directly into the blood. This was noticeable when people were testing benzine excretion before and after using isothiocyanates. Anyway using more fuel can only create more particulates even if they are smaller. The particles emitted by a diesel without emissions controls are basically soot which is heavy and falls to the ground. The treated emissions are lighter than air and tend to float in the sky. This is noticeable in places like San Jose from the observatory. If one drives up to the top of the mountain they can not see the city any more from the smog. People are breathing those toxins and to my knowledge there is no debate that smog affects peoples long term mortality and health span. Soot on the other hand would just end up on the ground and on the walls of underpasses with some of it potentially being kicked back up from traffic but would be filtered by the vehicle cab filter assuming one has the windows up. I would be curious how much more dangerous that soot really is than say brake dust.

Anyway, all interesting points and maybe some day we can get some empirical data on this provided that manufacturers do not tamper with testing and are not in any way involved. In the mean time I will just do whatever prolongs the life of the engine, gives me back fuel economy and keeps the vehicle reliable.