Was looking at the cobalt website and realized that it runs on regular. I find this odd for a FI car. Whats the SRT4 run on? I imagine that you could turn the boost up higher and run premium and get better performance all day long with no problems.
SRT-4 stock is usually 11-13 psi, the computer controls boost according to the outside temperature. The cobalt SS is at 12 psi, but you can't compare them in that way, because an SRT-4 with a 50 trim turbo running 10 psi pulled on a stock SRT-4.
I own an ION Red Line and use nothing but premium, it is what is recomended for the engine but the manual says you can get away with a mid grade octane. I also live in an area that has reformulated gas with 10% ethenol, but the boarder of the county west of where I live is not far away and they do not have reformulated gas so I try to fill up with non-reformulated gas as much as possible. I have read some bad things about injector problems from the reformulated gas. Enjoy those Cobalts when you get them, I am having a great time with my Red Line.