In my humble opinion, I would appreciate it if the air ducts actually served a purpose, but they don't. In addition, having air ducts at the rear of the car is completely daft considering the engine at the front. I am not a fan of them at all.
Regarding the light washers, my local stealer has put out three Cupras with Aero kits in 2007 and this is no different from them with the exception of the centre exhaust.
One thing I have thought about is that if these kits are dealer fitted, then the rear silencer must be part of that kit and therefore probably pretty expensive over and above the price of the rear bumper, and they would have to cut in to the original one piece exhaust system to do it.