common rail diesel injectors kinda work like gasoline fuel injectors. to get more fuel out of them, open it longer and boost the rail pressure. on the duramax, the first power box that came out was the powerplay box. all it did was boost the pressure in the fuel rails [it also had the side effect of causing fuel leaks on the low pressure fuel return plumbing when cranked to max] . boost the pressure up and electronically advance the injection timing a tick more and you will get more fuel in. now, there is probably room for improvment on the injector tip, like tinkering with the spray pattern or increasing the # of holes in the nozzle.