I would agree with leveecius, you would also want to incorporate a bigger bore to. Thats what V8 gurus do to the bottom end. Up their compression ratio for higher end hp. Just be careful to have it all drawn out far as fuel, air, and spark.
Most of 4 cylinders that up the compression ratio, generally add bigger valves and valvetrain to accomodate the bigger compression. You have to remember if you get higher in compression to consider a different sized head gasket, yet along with longer cam lobes. This will help out tremendously for serious gains. I was thinking of staying N/A, but its a lot of parts to build it up right and keep as a daily driver.
The only downfall on having longer connecting rods is that you have a higher risk in breaking it, if its not tolerable to higher stroke. You have to weigh in all options: air/fuel ratio, heat of spark plugs, ignition timing (23 degrees after TDC), transmission, suspension, it all needs to be balanced for the power your wanting to throw into it.
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