The LB7 is unique in the Dmax lineup as it is the only model that uses the VCO style nozzle. The SAC nozzle is the mainstream nozzle used by Bosch on all other Dmax. It is my understanding that the SAC contributes a small amount of additional hydrocarbon emissions due to fuel lingering in the SAC. The VCO nozzle was designed to eliminate this. The catch is that with the VCO is that not only does it have to close off all 7 spray holes simultaneously, it also needs to deliver/distribute the fuel evenly. The SAC type just turns the fuel off and on.