Summary: 2011 VW CC, looking to upgrade turbo to K04. Must I upgrade Intercooler, Air intake, Exhaust, or get computer hardware???

I have a 2011 CC with a bad 'Turbo and converter' according to the dealership. The check engine light is on for underboost and oil is slowly seeping out the back side. I already tried replacing the diverter valve hoping for a cheap fix, but it looks as though I must replace the Turbo. I have decided to upgrade to a K04 from ECS tuning but I am curious if I must upgrade other parts of the VDub as well. Such as Cold Air Intake, Exhaust system, New computer software, or intercooler... These are all planned for the vehicle at some point in its life, but I am curious if they 100% have to be done when the new turbo is installed. Any help/tips on the subject would be great. I am planning to undertake the project myself, so I am also looking to make contact with anyone who has put a larger turbo on a CC or Passat or anyone who has tried and failed and thinks I would be better off paying someone to do it.... THANKS!!!