Tests carried out by automotive journalists have all highlighted the reduction in diesel consumption which is induced by the use of P-Tronic additional box-units. If you consume less, you emit less CO2 and so you pollute less.
It's logical. This is all the more true as the reprogramming of the injection as effected by P-Tronic power kits in no way alters the contents of the exhaust gas.

«The user pays less in fuel, and as a consequence emits less CO2» - La Libre Belgique