You really should consider replacing the springs ,shocks, struts and upper strut mounts all at the same time , simply because of the level of effort and that stocks shocks aren't going to give a the best ride with those springs. You will need at least camber bolts , and the toe in will have to be adjusted.
Don't forget an adjustable pan hard bar to re-center the body over the rear axle, lowering can throw it off by up to a half inch to one side.
2008 Metallic Alloy GT Convertible Premium
Show : black top| 18" bullitt polished wheels| CDC light bar and black billet replacement grilles | black/amber corner lights | GT500 rear spoiler| AH chin spoiler Go: FRPP CAI with StangHi tunes | Kooks LT's | FR500 axle back | Steeda Sport springs | Koni STR.t struts/shocks | J&M camber plates | UMI adj. panhard bar | LCA relocation brackets | GT500 LCA's | Hurst Billet shifter | 3.73 gear | FRPP axle girdle | Baer Rotors and Pads