Racechip has just released a chiptune for the new Panamera 4S diesel. I know, not in the same league as ABT, impact on warranty etc, but still they've been in the business for quite a while. At least it gives some indication that this engine is quite easy to tune.

Panamera 4S Diesel tuned with Racechip: 505hp/1037nm

More info here (in german)

http://www.auto-news.de/tuning/anzeige_Racechip-tunt-McLaren-570S-und-Porsche-Panamera-4S-Diesel_id_39487