Welcome first sir! That's great to hear you picking up his cobalt. Its the chevy cavalier perfected in my opinion. Your 2.2L with just a few bolt ons can maintain great fuel economy, some on here are known to carry more MPG than some hybrid vehicles out today. My record was 39.6 Hwy with just a intake, header, and catback system.
Your son's SS isn't that much more in power. You can stay with him on bolt ons and a proper tune.
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