All the struts and shocks across all Cobalts are directly interchangeable. Since you have lowering springs, you'll be good to upgrade to the FE5 stuff (it's not recommended to upgrade to FE5 struts & shocks with the FE1 springs). Like RRob said, the 08+ is the best handling FE5. That's off the SS Turbo. They can be found at crate engine depot or amazon.
Anything aside from the struts and shocks is optional. I'm still running FE1 control arms, endlinks, etc. with the FE5 struts & shocks and Canuck Motorsport springs. No problems so far.
Believe me, these cars have a habit of growing on their owners. Your feelings will only strengthen over time...
Last edited by Parthros; 04-04-2016 at 02:18 PM.
Reason: Corrected errant info