StormCat produces bottle holders specific for the GT. They hold 12-16 oz water bottles or 12 oz soda bottles. He has them in silver and carbon fiber. They attach to either side of the center stack. Both he and I have pictures posted. They take about 10 minutes to install, and can be removed just as quickly. You need to look at the pictures to understand what they are. Cups won't work in them. I saw them 3 years ago when StromCat first prototyped them and fell in love. They are excellent and I use them every time I'm in the car. Do a search for bottle holders.
If you must have a cup holder, you can do what the Ford engineering team did and put a roll of duck tape on the center console.