My favorite mod were the rear swaybar, lowering springs & bigger rims/tires ... that dramatically improved the 'fun factor' of driving my car. It makes a dramatic difference in how the Mustang looks (stance is key). The short-shifter is a 'nice to have' but doesn't make a big difference. CAI & UDP improve performance (and gas mileage as a bonus), but gears are king because of the torque multiplication factor. Beware, though, they will reduce gas mileage (that kind of performance isn't cheap or easy).

 

If you order anything from rpmoutlet expect a 6 month wait.