The engine is increased to 520 horsepower with a tune and exhaust although there is no dyno to confirm it. Brabus won't short change anyone but it would be nice to see how they compare to other tuners especially for the money. It is not difficult to guess that the Brabus tune is more expensive and likely not as aggressive.
Sport springs are available for SL350 models (not sold in the USA) and electronic lowering modules are available for the other models. This particular car was lowered on Brabus 20 inch wheels to complete the look.
Overall, there are better options for the new SL out there at a much lower price point.