If we look at the MC in the following link we can see that its different from what we have on the SRT6. I ordered the MC from Cardone and I got the wrong part, they swore up and down that it was the correct part. I think that I was dealing with a rep who thought that the Cardone database was perfect. I too was trying to solve the low pedal situation, I never did.
It has been suggested that the Booster could be the source of the problem, who knows? I'll keep at it though.
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The above link is from the Mercedes SLK32 AMG Roadster EPC ( Electronic Parts Catalogue) here. CLICK
Here is the matching site for the SLK320 Roadster EPC. CLICK