Apparently you don't quite realize how fast 80 MPH is. If something happens at 80 and you have to react quickley, you have a HUGE chance of ending up dead. What happens when you slide into a tree sideways at 80? Even 50? You die. What happens when you slide off the road sideways? Your car rolls, you either get disabled, maimed, or killed. Period.
I am only 20, and I don't claim to be a saint behind the wheel. But being 16, and scoffing at the idea that your dad wants you to keep it under 80, in my opinion is a recipe for disaster. Look at this:
http://www.allfordmustangs.com/forums/showthread.php?t=42578
You've probably seen GumDropLarry on the forums quite a bit here, this happened at "only" 60 MPH, on his 19th birthday.