The high-performance Audi RS6 Avant gets a power boost from the specialists at O.CT Tuning. To be more specific, the stock 4.0-liter twin-turbo engine offers 560 horsepower and 700Nm of torque. After some tweaks, such as a revised ECU unit and a sports exhaust system, the V8 powerplant delivers 680 horsepower and 880Nm of torque.