Porsche had to have the Auto cut out between 30 and 70 kmh I think or something like that.
Then the switch came along and all you have to do is ask you dealer to remove the auto cut out so that the driver becomes the only one who choses between sport and normal noise at the touch of the switch.
I'm not a 100% but that's what I had done on my car.
It's all done through the computer they use to diagnose the car, so it's also very straightforward.
Hope this helps.