Chipped or remapped cars generally are set up by the tuner so that they work within the tolerances of the factory hardware. If you were to fit a higher flow pump; along with high flow injectors, you would need to
1. increase airflow with more boost or mechanical work (or both)
2. alter the fuelling to cope with the extra available oxygen
Generally with tuning the first goal is to get more air into the engine and then adjust fuelling to suit.
So, basically, you'll be revisiting your chip tuner or remapper when the new pump is fitted if you want to take full advantage if it.
Incidentally, your A4 - petrol or diesel?