Here is a thread about a G5 2.2l that got dyno'd before and after adding a Trifecta tune. It looks to have had an intake, exhaust, header and hi-flow cat and then added the tune. The tune only added 2 hp and 3 tq peak and not much more even at the non peak areas lol.

http://www.g5club.net/showthread.php...)-Tifecta-Tune

I do not know what our cars dyno at the wheels stock though so this 142hp might be a decent improvement over stock. But since there is not the support for our cars as there is for the Cobalt, the prices for equivalent items for our cars is most likely going to run over 1k for this lol. Although in doing some looking around it looks like the early 05-07 Cobalt/G5 2.2l used almost an identical exhaust system after the cat and might be interchangeable with minor tweaking of the hangers on the back side of the muffler. But even then there is but only a handful of cheaper exhausts to choose from. They are only in the $130's - $160's though. 2.25" piping of claimed stainless. Could always get the system for the piping and put on your muffler of choice for less than the CGS axle back kit.

 

Oh one question? Did you get the tune for 87 octane or for a higher octane? If higher octane have you ran a couple tanks yet with the higher octane?

 

I installed a K&N 57-3056 Filtercharger Injection Performance Kit Cold Air Intake, on my 2007 2.2. It is not listed by K&N but it fits. Better low end tq, and mileage went up a little. Has a nice sound from a stop.