The most popular brand of springs for our cars are the Eibach Sportlines and they drop 2.0 in the front and 2.5 in the rear, it's really mroe or less prefference but any drop is better than stock right?
I think lower on the rear looks alright on the cobalt because of the forward/downward angle on the upper body. It kind of levels it out a bit and makes it appear a little bit more mean. Plus likewise it's better weight distribution for FWD. IMO