I wouldn't worry about upgrading brakes unless your dead serious about pushing power. Im not talking about Header, Intake, and Exhaust combo, more like laying down another 100hp and tq to your car. Otherwise, just get better brake pads if daily driven.
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