There are a number of places that have experience dyno'ing MB's. The difference between them and the ones mentioned is that the ones you listed are aftermarket manufacturers.

The MB boy's had a dyno day in Atlanta a year or so ago. They dyno'd:

4 SLK32's
2 SL65's
3 SL55's
A couple of C32's, C55's and CLK55's.

Everyone got 3 full runs. If I remember correctly the SLK32 guys were putting down between 292-300 hp.