Dyno-Comp did dyno the headers on a Dyno Dynamics and got a baseline of 440 horsepower to the wheels. They then added a tune, filters, and their headers resulting in 531 horsepower at the wheels. 91 horsepower at the wheels with bolt ons for an M159 V8? That seems quite optimistic with a 440 wheel Dyno Dynamics baseline and BenzBoost looks forward to third-party results verifying the claimed horsepower gains.
Additionally, due to a single dyno with a tune, filter, and the headers versus the stock baseline it is difficult to evaluate the impact and quality of the header design alone. More useful data would be a dyno with the headers alone, then with the filters, and then with the tune to see the changes at each individual stage.
Regardless, it is nice to have another header option for the SLS AMG on the market. Pictures, dynograph, and video below.