Yes we only have a CP3. That's it. It vacuumes (no pressure) the fuel from the tank and then pressurizes it to the 4,000-26,000psi mentioned earlier. You can add an aftermarket lift pump to push fuel to the CP3 to the tune of around 8-12 psi. The cp3 alone works fine but can't suck enough fuel by itself for higher horsepowers. The airdog also lets you separate the water from the fuel and run it through another filter as well as making it easier on the cp3 to function.thanks guys i new the cp3 wasnt in the tank i just wasnt sure if you deleted it when adding an air dog i didnt no that the cp3 created that much psi. So the duramaxes only have one fuel pump then just the cp3?