Unfortunately there is only one camera angle so it is difficult to see the car length difference but it appears the C63 gets a small lead and then the Mustang catches and passes as speeds rise due to its horsepower advantage. To reverse the outcome the C63 would likely need the 3.0 liter Stage III setup which is capable of over 630 wheel horsepower on 91 octane. Videos of the Weistec Stage III supercharged C63 Black Series that was in attendance to show the difference between it and the Stage 2 will be coming shortly.
Enjoy the race. Thank you to the Mustang owner @kaane for the video.