I would go buy a new rack from Thule or Yakima. I prefer the Yakima with a Qtowers the best. The factory rack is to small to put anything on. Mine was never put on my car when I bought it. (Black rails were installed, but the bars are still in orginal box). If I ever get the time and drive, I will be removing the black rails also.
Go with an aftermaket rack though. I can fit a long box and two bike on my rack, but I couldn't even fit the box on the factory. Also, there are a lot of problems with interfence with the spoiler and the factory roof rack. Everything hange off the back to far.
Do a seach for roof racks and you will see what the problems are.