I believe Apex (not apexi) has range from 2-2.5" drop. It will be approximately 1-1.25" tire tucked, so go with small wheels/tires. It will ride like poop though even with FE5's since the spring rate is horrible. I would stick with a better brand name like ZZP, Powell, Eibach, or ARK. It wont be much of a drop, but noticeably improved on handling.
2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille