Off-Road Navigation Option
As I mentioned before, the Off-Road Nav is already integrated into the PCM2 software and has to be unlocked with a special code from Porsche with the Piwis system.
To my knowledge, this option wasn't officially available for retrofit when I did it on my car but maybe now...just ask your dealer if you're interested.
Advantage of the Off-Road navigation: you get a digital compass and the display also shows in which angle the front wheels are. You also get a precise GPS position and the height above the sea on the same page.
But the best thing is actually: the Off-Road navigation allows to backtrace a route if you activated the backtrace option.
Meaning: if you travel through unknown territory, you just activate backtrace and the Off-Road navigation leads you back exactly to the point where you started.
It works up to a distance of around 170-180 kph.