You won't be short of mod suggestions on here but the most common are eibach lowering springs and a re-map. The springs make the car look how it really should and improve the handling in the corners. They won't affect any warranty as they are Ford approved.
There are lots of re-map choices but the most popular seem to be Mountune (good if your car is still under warranty as it's Ford approved), Dreamscience, Code:Red and Bluefin.
If you have the money, you can turn it into a completely different beast!!!