I guess my question is how does a fueling box get more fuel in through stock injectors? Or are they(fuel boxes) just less effective with stock injectors, and will only do what they can based of the physics of (same pressure + same hole diameter = same fuel amount) Thus the only adjustable variable with stock injectors would be a longer injection duration, thus retarding the timing, but creating much more fuel in the combustion chamber?

 

Well, I don't know the last part of your question but from what I've read, some boxes will yield higher numbers with stock injectors. For example, TST Comp will gain you closer to the 180hp advertised number with stock or small sticks than if you're running big sticks.

I could be completely wrong though.

 

You sort of hit the nail on the head. You are basically just adding duration to the stock injection.

Now this does not retard timing. Timing has to do with when the fuel is delivered now how much. Adding duration simply allows you to add more fuel but you start at the same time as always.

Now to do this with the VP44 you are also playing somewhat with the solenoid pressures and it does slightly change the pressure at the injectors.

You can also advance the timing via the can bus or by calling for the injection on the pump to happen sooner.