Are you sure you know what AMG is?
That's a fake. It's nothing more than a badge. The only AMG tuned CLK that Mercedes came out with for that genereation was the CLK55AMG. It had a 5.4L V8 for starters, not a 4.3. Since the dealer is not selling this as an AMG, I have a feeling the previous douchebag owner put the emblem on to look cool. To answer your question, the onlky difference between normal 430's and 430's with fake AMG badges on them is the plastic AMG badge. Other than that, they're the same car.