I emailed CGS last week to ask about the clunking and they said they sold 600 units and mine was the first complaint. Suggested I check for a broken engine mount. They did offer a replacement filter without metal on it for their cost it is the same size.

Also, they have an HHR that hasn't had a problem.

 

I talked to them about this too.

I thought they were VERY rude. I would never deal with them professionally. Saddly, they have the only intake I like the looks of. (Not going to get into performance differences!)

I switched to the K&N mentioned above.

We also have an issue with the hood support rubbing. They deny that this is a problem too even though I've seen it on several other HHRs.

 

I have the CGS with the Outlaw Filter, when I first put it in yes had a rocking, banging noise.
But after I reseated all I have no problem, My Outlaw filter has the Chrome on the bottom. No rubbing at present anywhere, for a long time.
I have a 2.4 Auto

 

Mine rubbed. too.. thats why I changed to a different filter..

 

I had a problem with mine to begin with too and had the rubbing issue. I do have the 2.2L which requires some modifications to the CGS to eliminate the problems. Here's some of the things I have done that have eliminated the problem with the clunking and rubbing against the hood strut.

If you've got the rubbing against the hood strut like this



Go to Home Depot or Lowes and buy some pipe insulation like I did. (see upper left hand side of photo) You can buy a short length for a couple bucks and cut it to fit on the strut. It will soften the rubbing noise and protect both pieces from further damage. If you get the right size, it will wrap around the strut and you can peel off the plastic and the 2 pieces will adhere to one another. I put this on as a temporary solution after the above damage and decided to just leave it there.



If you have a 2.2L like mine, I have a how to do some modifications...see the thread below...paying particular attention to post #18 for measurements I used when making 2nd set of adjustments for 2.2L.

https://www.chevyhhr.net/forums/2-2l-performance-tech-5/even-females-can-install-cgs-3430/

I do have my Outlaw filter in there quite snug and have no more clunking, however, if you still experience some, take a piece of the foam used above to put between the filter and the inner portion of the body and that should eliminate the noise completely.

 

Mine was rattling, but it was the hood strut that was hitting it, i just put some pressure on the pipe of the CGS and push it to the valve cover just a bit, so far so good, I have the 2.4L

 

Well when I built mine, I had the same little rattle, came to find out where you mount the intake to the valve cover, the bolt you use needs extra washes to fill in the gap under the mounting bracket to make the intake more stuff, and to help with the plastic on the valve cover from bending inward.
https://www.chevyhhr.net/forums/general-hhr-4/my-intake-8343/. This is on my 2.2l

Hope this helps!!