Actually, with ford making the shelby come with 3.31's they probably save you an amount of money that you are going to have to spend to install a set of your own gears. because the gas guzzler tax i think on the gt500 is around $1,300 or so. but on other cars i have seen it upwards of $2,400!!!!
2007 Mustang GT Convertible Stage 0 E-Force #402 Supercharger, Brenspeed Tune (435/400), GT500 Fuel pump, Clutch Delete Option, Roush Front Fascia, Brembos, California Dream Hood, Qwitch latch flush mount hood pins, MRT Light Bar, J&M LCA's, BMR UCA, UPR catch can, 6000k, Pypes Bombs, Pypes X-pipe, Airbrushed Flame pieces under the hood, Clear corners, GT500 shocks , FRPP P-springs (rear), BMR Adj Panhard, E-Force engine covers
2012 Ford Focus SEL 5Dr with MyFordTouch, Auto-Park, 303A Package,