External improvements include an optional SVT Performance Package, which includes Goodyear EagleF1 SuperCar G: 2 tires, all-new lightweight 19-inch forged-aluminum wheels in front and 20-inch forged-aluminum wheels at the rear, a 3.73 rear axle ratio, and performance tuned front and rear shocks along with stiffer springs. The package includes a unique rear spoiler Gurney Flap for improved handling, slightly revised front and rear fascias, a new pedal box for improved clutch use, slotted brake dust shields for improved brake cooling, standard HID (high-intensity discharge) headlamps, MyKey programmable vehicle key, integrated spotter mirrors, and fold-down rear headrests. Optional is a glass top roof, previously available, starting in 2009, with the Mustang GT.