So, here the info from ziptuning:

"De Ziptuning uniek gemeten acceleratietijd van 0 naar 100 km/uur na tuning is 6.2 seconde. Origineel was de acceleratietijd ongeveer 7.1 seconde.
In de tussenacceleratie van 80 naar 120 km/uur zal de verbetering ook groot zijn, u merkt een duidelijk verschil. De topsnelheid stijgt van 235km/uur naar 256 km/uur"

Meaning:

"The measurements made by Ziptuning in regards to the acceleration from 0 to 100km/h after tuning are 6.2 seconds. The original acceleration was about 7.1 seconds. The biggest improvement is in the retakes from 80 to 120 km/h, you will noticed a clear difference. Topspeed will go from 235 km/h to 256 km/h.

They are also giving a reduction of diesel comsumption (at normal riding, so no kick downs ) of about 8%. If requested, the original software is put back for free.