what should I do to my 2008 Chevy cobalt Lt to max it out speed wise everything is stock

It doesn't look like you need to go faster, but a chip would do the trick, there about $400.

Everything! The skys the limit. Check the "Tuner" magazines, & see whats availible for you car. Like cold air intakes, tube headers, exhaust systems, ignitions, cams, bigger cc fuel injectors, even turbo's & nitrious.

But seriously, if you really want performance, start by selling your LT and buying an SS. You'll have the more performance oriented 2.0 as a base as well as the factory's performance package. Add to that and you'll have a serious performer for a lot less work and probably a lot less money. The 2.0 can easily be run up to 7800 with an aftermarket ECU (visit ZZ Performance) and that's where you'll find a lot of horsepower hiding. I'm not sure how your 2.2 will feel about the extra revs, although it is a very tough engine as well. Make sure your timing chain is good before you get too carried away. You won't like what happens if you don't. I didn't.