Normaly you can get 17's on a mk2 without any problems, although if it isnt lowerd it will look a bit silly, Im not to sure how its going to sit with the adaptors on because it wil change the et mate! Your going to have to play it by ear and see what you come up with!
You can normaly pick up cheap ish rims if you decide you dont want to go ahead with the 17's anyway