Mercedes do use the same engine as different 'capacities' in several models. The engines are usually the same capacity, but will have other differences between them. These will include ECU mapping, injectors and possibly other things of which I'm not aware. So, while remapping your 200cdi will get you some gain in performance, it may not bring it fully up to the level that you'd expect from a 220 and certainly not a remapped 220. The best thing is to talk to one of the tuners and see what they can offer. Alternatively, go to celtictuning.co.uk and use their online gizmo to show you what you can expect.