Generally speaking, the ideal performance alignment for me is zero toe (so the wheels are aimed straight ahead), negative camber (top of the wheel angling toward the car), and positive caster.

Caster and camber also have a working relationship since positive caster produces more negative camber on the outside wheels, which leads to more stability and grip in the corners.

Negative camber is a measure of how drastically the wheels tilt inward at the top, almost as though the tire is leaning against the car. But what's the point of that much negative camber?

What sort of tune do you want on the suspension? What a Mustang needs is mainly more negative camber while cornering, which means a bit of static negative camber and considerably more positive caster.

Caster and camber also have a working relationship since positive caster produces more negative camber on the outside wheels, which leads to more stability and grip in the corners.