Just to clear up a few things.
All Mercedes cars are firstly limited to 155mph, including the AMG's. However, if you ask AMG, they will raise the speed limited to a maximum of 300kph or 186mph. This is the maximum limit that which the car can go safely due to the tyre's inability to carry heavy loads at speed. One last exception, if some magazines would like to try the top unlimited speed of the car at Nardo, then they have to ask AMG for a special car which has no limiter at all. Such was the case here. But this sort of completely unlimited car will never find its way into a customers hands no matter how much money you have, simply due to the tyres and legal and safety reasons. But Brabus is always breaking rules.