We really need someone to make a intake tube for the stock airbox like ZZP does for the Cobalt. That's where most of the gains are to be had.

 

K&N makes a kit for around three bills. Taller lid, filter, and refined tube. It would be great if you could buy the parts separately but nope.

 

You can buy these parts separately. I called K&N directly today. I just orderd the pipe, the two hoses and the vent. I can get the clamps here at home. If you look at the install sheet that is parts B,G,E and D. Those four items came to around $140 so we will see how it all works out next week because thats when I should be getting those parts. I did already have the filter. Don't feel you really need the lid. Yes, and before everyone start saying I'm going to get codes, I currently have the K&N filter in my car and I have never thrown a code once.

 

I have to agree with foolmoon, about Hahn saying that chevy got it right on the underhood air intake. all the underhood air intakes I have seen, all have the same problem, heat soak, and the same restriction as a stock setup. Basically, they are just for looks, and maybe even hurt performance.
After doing some research on the airflow under the HHR-SS hood area, I went down a different road. I fabbed up a hood scoop fed CAI, with a very large AEM/Fram filter, than uses the stock airbox[except for the lid]. The very large hood scoop [when moving] forces a very large amount of cooler air, directly onto the filter, and forces some of the hot air out from under the hood. Seems to work real good, and so far no problems or codes. Air intakes than take in hot underhood air don't work, no matter how big they are. Stock chevy, takes air from inside the wheelwell for that very reason.

 

I totally agree with you. That is why I'm just changing the one pipe that is suppose to allow more air in. Otherwise everything else works just fine.