I have just received my kit two days ago. I am not lowering my car. From what everybody says, it is not that bad. You have to take curbs and speed bumps at an angle. The front is usually not the issue, if you are going to scrape anywhere its the back of the side skirts, because that area is much lower then stock.
Official Powerhouse Amuse 370z Thread
FLY1 makes scrape plates for the front and the sides.