Cjz 2oo4 said:
That's something to work with, and can be used in many different ways.
For example, you could buy different wheels (say some 17"), tires to match, and do the
suspension (springs, shocks/struts, sway bars). That would give you a better looking car, that would handle better too. But it wouldn't make it faster.
If you don't care for looks as much as speed, there is a different route. You could add a Cold Air Intake (CAI), a aftermarket UD pulley, get a true dual exhaust, and maybe different plugs and wires. That should make the engine run smoother. With the rest of the money, you can buy yourself some gears and a t-lok, which will improve your start.
Those are the most common options. If you want some real engine work done, you can got to
www.supersixmotorsports.com , or
www.rpm-mustangs.com . They do some porting, polishing and that kind of stuff.
So that's all I can think of.