There is no chip for the HHR, only a handheld or a custom tune. There was one here getting a handheld, but haven't seen any results from it yet.
Best bet is a tune.
2006 1LT, 5-Speed, Born 12/9/2005, but hidden in the deep Florida swamps.
Black chrome lower billet, black chrome custom grill, K&N, LED tails, stock fogs on aftermarket wiring kit, 48" RECON "Big Rig" running board lights, 18" Cobalt Polished alloys, turbo tech sway bar. all exterior lights swapped to LED's, 35w 5K DDM HIDs. Upgraded to SS front rotors.