The same thing looks like it will take place with the AMG GT and the W205 C63 AMG. The C63 AMG M177 V8 will get 476 horsepower to start with. This places it ahead of its rivals at least on paper. Keep in mind the new M3/M4 S55 inline-6 motors are severely underrated showing as much horsepower at the wheels as they are rated at the crank. For the Mercedes C63 with 476 horsepower to beat the M3/M4 the C63 will need to dyno at least 450 wheel horsepower considering it will not have a dual clutch transmission and that it will likely be heavier than 3562 pounds.
If BenzBoost were to guess, the F82 M4 and W205 C63 are going to be about even in acceleration just like the the E92 M3 and W204 C63 AMG. Mercedes-Benz will offset this as they did previously with a performance package. We will have to see if the package is just software that raises output or if Mercedes is getting the same 510 horsepower as in the AMG GT M178 with actual hardware changes to the motor as they did with the P31 option on the W204 generation C63 AMG M156 V8. Let's hope they are not going for a cheap money grab and it is not just software.
BenzBoost confirmed a performance package for the W205 almost a year ago that the industry seemed to ignore. No output figures were quoted but our source gave us the figures we are quoting now. It seems unlikely that Mercedes will exceed the AMG GT's figure of 510 horsepower as that will upset AMG GT owners and the set hierarchy. Expect around 510 for the C63 AMG S if they call it that with the option standard similar to the E63 AMG S models or they may just add the Performance Package as an option. Either way, you will be able to get more power with a Mercedes warranty attached if that is your thing.
Regardless, despite BMW's low crank rating their cars are much more powerful than the crank horsepower rating would indicate. Mercedes-Benz is aware of this. BMW is aware that they are aware and may ready their own Performance Package option to fight back. This sure is fun, isn't it?