HUD would be major project that would also be a major expense. Adding Navigation would be easy. See link below.
http://www.ebay.com/itm/14-15-OE-GM-...item3f3cc98a94
I took it a step further and upgraded to get Apple CarPlay (2016+) which was a bit more extensive (had to replace Radio Tuner & USB port in addition to HMI module).