You will need the harness no matter what to get the cup holder lights working, John will help you with that. If you also want to add the media bin light and glovebox light you will only need (1) ambient light. If you want to add a light to the upper glovebox like I did, you will want (2). John will include a second harness for the addition of the lights if you want them, based on what lights you want to add.
Basically, one harness will run the cup holder lights and the other will add the media bin light and glovebox light (s). The are both plug and play harnesses. The only modding you will need to do is cutting holes for the media bin light (if yours doesn't have the knock out piece) and the upper glovebox (no knockout - have to make this hole).