Ok sorry, I will try and explain.
The tuning boxes work by increasing fuel pressure, so that you are constantly injecting more fuel than the ECU thinks. DIesel engines are really quite crude, even the latest tech in the SQ5. More fuel = more power. But it has its side effects in that too much fuel will raise exhaust temperature and internal smoke will dramatically reduce DPF life.
AFR - air/fuel ratio is a measure of how much fuel the engine is burning. I asked for a graph because quite often the tuning boxes put in so much fuel that they kill DPF's.
With a remap, we control this very precisely The above plot is a very safe calibration. We can run much more, but that would require a richer mixture.
Rick