AMG_Adon

I am torn between the 2 I wanted more power out of my clk but a tune and headers is not going to cut it for a n/a engine so im considering either a cls55 or a cls63 I believe both cars have the extra power bump im looking for and I would be content I wanted to get some of the AMG owners to give me some feedback these and what to look out for when purchasing I don't want to jump the gun.thanks in advance