The extent of the modifications to this F13 M6 is unknown. A Gruppe M carbon air intake system is clearly visible and one would assume for 803 lb-ft of torque at the wheels exhaust modifications are necessary. It certainly would be nice to get a list of the full specs.
Regardless, the numbers show 673 horsepower at the wheels and 1090 newton meters of torque at the wheels. How Evotech is getting such absurdly high torque figures is anyone's guess.