Edge EZ adds fuel pressure only. Thats it..... If you are looking for 65 +- horsepower it is a great box. I have been running one for months and am very happy. I would suggest installation of and EGT guage even on a stock truck before the install of and EZ.
I can hit 1200* with no EZ pulling empty in fourth gear. I think it happens a little easier with the box.
Basic idea I have about how it works is:
Fuel pressures are raised up in the common rail. Then since each injector is fueled by a seprate servo the higher pressure increases the amount of fuel that is put through the injector. By increasing fuel, you increase power.
Hope this helps, Greg