I have an 04 2.5 T S80. I want to give it to my son, a new driver. But I feel the car is too powerful for a new driver. Can the turbo be disonnected without damaging the engine. Alternatively, can I reprogram the car's software to limit the turbo?

 

NO.

The dirveability of the car will be gone. If you want to give him a non turbo car then buy him one. Don't mess with that car to try and give him something non turbo. It wont be worth the time and money.