True, I was assuming that a lot of parts on the 2C were locally manufactured. If not, it should in principle cost nearly the same.
Unfortunately, we can't compare just the injection pumps of the two injection systems. The VE has the pump and distributor built into the same unit. All you need are high pressure lines and mechanical injectors. The CP3/4 pumps need a a fuel rail with pressure sensor, and solenoid or piezo injectors. So it would probably be better to compare both systems as a whole.
Even then, it's a bit like comparing apples to oranges (maybe not oranges, pears perhaps?) The modern counterpart has got performance and potential fuel efficiency as its plus points. The older system has "repairability" and relative robustness as its plus points.
The one reference I heard to sulphur affecting the FI system was by progressively blocking the injector orifices over a relatively long period of time. But this was on a Siemens CR unit on a 1.5 litre Renault engine. It could be that the two systems (VW and Renault) were different enough to react differently to the presence of sulphur in the fuel.
There is a little anecdote here as well. My University has two diesel engines on dynamometers. One is the aforementioned Renault unit, while the one that I've used for my studies is a PSA DW10B (2 litre CRDi diesel). My work was related to water injection. I did tests using intake water injection which worked pretty good. A colleague of mine did some tests after me with emulsions (10 - 30 % water to fuel mass ratio). The Renault engine enjoyed the mixture and ran without hiccoughs, and the results were very encouraging. He then tried the same thing with the PSA engine, the aim being to add to the data pool. The engine did not like it at all. More precisely, the pump. 40 minutes later, the pump gave out. He installed a new pump, thinking the old one was on the way out, and the same thing happened in 45 minutes. The engine has got its third pump now and there are no emulsion tests in the forseeable future. One day we might come back to it with a special pump or something, but until then, it's just manifold water injection and cold EGR to play with.
For interest:
http://www.bosch-motorsport.com/pdf/components/Diesel_System_Components.pdf
