nx2k japan made with abs ad22vf. nx2k u.s. made with or with out abs ad18. I've been talking to my local nissan parts guy and researching to find the cheapest route possible to do this upgrade. The wheel fitment is because the 14" nx2k alloys were made specifily to clear the larger brakes. Just about any 15" will clear fine as long as it has a +35-+40 offset +40 being the max. As for the fastbrake babk it says they are designed to fit behind 15" rims but I've read that some people are having fitment problems do to there wheels offset. They are haveing to but spacers to get them to clear their 15" wheels.16"+wheels shouldn't have any touble though. I think the max offset for the 15" wheels and the fastbrakes babk is like +35, but dont quote me on it.That is what I concluded from what I've read.