Check these out. I hope they make them for our trucks soon, but at a 1000.00 each. and a 30% improvement in fuel economy plus more power. I might buy them. The most interesting part is that they will convert a gas engine to diesel, confused on that.

http://www.greendieselcorp.com/index.html

 

Its no secret that the higher the pressure the smaller the orifices you can use to make the fuel atomize better. The finer that fuel mist the cleaner the burn. youd gain power and mileage from that along with a reduction in particulate.
My pump is probably going bad.. even with DDP2's which are supposed to burn cleaner I see a lot of soot. Im guessing the injection pressure is low.
Im not sure how the heck youd convert a gas motor to diesel. I mean the compression required to ignite the fuel isnt there unless you shave the head and use different pistons. Not to mention the extra loads which require heavier wrist pins and crank. I think that part is false advertising.
Common rail systems inject at a very high pressure and theyre commonplace now.
Only downside I see to raising the injection pressure is the extra cost and complexity of the pump and the kinds of fuel you can burn. Supposedly there are issues with biodiesel and veggie oil at high pressures.