To be honest i have no idea. Unless there are any other W208 owners who have tried on here. I suppose it could be modified to fit but a picture of your current exhaust setup would be ideal.
It should fit so long as your clk is not a v8. Remus list exhausts under the same part number for both the clk and 202. My Remus was quite a big bore and came with a reducer for use with the 2.0 4 pots but bolted straight on my clk as it was the 3.2. The only problem is the single round cut out on the rear clk bumper looks a bit naff with the dual pipes but at that price !