When imagining a 6.0-liter twin-turbo V-12, 621 horsepower and 738 lb-ft of torque sounds pretty good, doesn’t it? Mercedes-Benz AMG thinks so, too, and that’s what the SL65 AMG roadster delivers. Bodo Buschmann thinks otherwise. His tuning house, Brabus, has taken AMG’s most powerful roadster and upgraded it to 788 horsepower, or 800 PS (Germany’s [.]