4xquadrod-there is an excellent articile on the 3rd gen hop up boxes in the latest TDR mag. In short the boxes out now raise fuel rail pressure (over factories 23,200 lbs) to push more fuel thru injectors. The boxes under development change injection pulse width (timing of fuel into injector) and the pressure of fuel going into injector (but not higher than factories 23,200 lbs). Problem is as the ECM controls everything the vendors are having a hard time bypassing the dreaded codes that are thrown when comp code unlocks the wrong keys... . 
