??? About the cobolt SS

My buddy just bought a cobolt ss and is woundering what it can take stock and what parts to put on it to make it even faster? He already has the smallest pullys you can put on the stock supercharger is that good?

He may have trouble with his AFR's depends on the pulley size, for more info check here

http://www.gmperformancedivision.com/performance_articles.aspx

look at the LSJ 2.0