Hopefully the stock HHR SS intake is better than the Cobalt. I heard from a Detroit insider that the intake is so restrictive, the stage kit hardly made a difference. This would explain why a revised intake will be part of the Cobalt kit.

2005 GTO's had issues with some aftermarket intakes altering the MAF calibration to the point of negatively impacting power over a certain range. In a perfect world, there is a minimum of 12 inches of straight flow before the MAF sensor. The more the stock intake deviates from that, the more fudging has to be done in the factory MAF table, making it more vulnerable to unexpected changes in airflow.

 

Before...

Here is the after graph. (I removed the DP because it was too loud for my liking)