Sorry, I have no data on the Carrera GT. I checked my notes again from when ordering the 4.0 and my memory was not entirely correct: AC: 18 kg, Rear roll cage: 20 kg, floor carpets 2 kg, Standard radio 5 kg, Nav with Sound package 11 kg (6 kg more than the std radio). With these changes Futchs car should weigh: 1360 kg + AC 18 kg + rear roll cage 20 kg + 30 liters of fuel 22 kg + Nav with sound package 11 kg + Full leather 4 kg = 1435 kg. So it is actually lighter than it should be - you got the leather and the Nav package "for free"!