The Bugatti Veyron gains an additional 250+hp (stock 1001hp).
Stock Veyron: 60-130mph 5.8 seconds
Stock Supersport: 60-130mph 5.1 seconds
ECU Tune: 60-130mph 4.4 seconds
The Bugatti Chiron also gains 250+hp. This model can be programmed via OBD2.