Awesome car
But 830hp from a BMS piggyback, catted downpipes and a Akrapovic exhaust... ????
The most powerful S63TU M5/M6 engines so far has both a ECU flash tune (the so called "press tune") and a external boost controller. Those cars have been dynoed at a maximum of 645whp which translates to a bit over 700hp at the flywheel (approximately 700-730hp).
And on the BMS site the tune for the M6 is stated to have 631WHP.
To end up at 830hp the drivetrain losses would need to be at 24%...