might add a quiet resonator. Thats what I did when the first mufflers were too loud.

 

And did it work to remove the drone sound? The muffler is not loud if you were outside my car as I drove by it would be a little louder than a stock hhr, which is what I wanted, a nice little roar. but in the car its like a subwoofer staying on during certain rpms but it's not crazy drone, but it can be annoying.

What resonator should I use, and it to replace the one I already have or to add an additional one?

 

You'd have to add another one if you want to try to get rid of the drone...but if that's the case you should have just kept your stock muffler. I'm pretty sure you're going to get some cabin noise with any aftermarket muffler you go with. These wagons don't seem to be as well insulated as other cars I've owned, especially in the rear of the car. It's hard to tell by the video but something as simple as adding a new tip to the muffler might help. I know they make tips that have built in resonators.

Here's a video of my HHR with the factory muffler with resonator deleted...

Here's one with the factory muffler, resonator deleted, added K&N intake...

And here's one with resonator delete and added Magnaflow muffler. Of course you can hear the exhaust well from inside...

I've had the Magnaflow on now for a little over a year...it's broke in nice and sounds great! I've since added a different tip and I swear it sounds better with the new tip.

 

Well I called dynomax and they told me the super turbo is designed to not have any drone, and to see if I had any solid mounts that would be creating drone transference. Also my muffler guy is also shocked that there is drone so he said to bring it back and he would take a good look as to what might be going on. He is a famous muffler guy who teaches college courses on the science behind an exhaust system, so hopefully he can figure it out.

I should be taking it back to him tomorrow so I'll keep you guys posted before I try anything else.

 

Borla is super discounting there remaining stock of cat back all SS systems for HHR's.I just bought 1 for my 2011,sounds good, increased HP and my MPG went up!!

 

So Im going to add a quarter wave tuner right by the muffler to eliminate the drone frequency while keeping the same tone. It will be on tomorrow I'll keep you posted.

Similar to this:

And remember I have a non turbo 2.4l

 

Cat back systems on our wagons have shown minimal HP (3-5 hp) and MPG increase...did you dyno before and after?

 

I'm not doing a cat back just a change of muffler to get a nice sound not for performance but it's a plus if there is any, but now that I have a nice sound I'm putting in a quarter wave tuner to remove the unwanted drone.

 

So quarter tuner didn't work to remove all of the drone. It may have removed the drone at 2500 rpms but as soon as it hits 3000 + rpms it's back. And sometimes at 1500 rpms it's appears at a low volume but only sometimes.

 

Sadly this experiment has cost me $226 and I think the only option besides putting the stock muffler back on is, trying to get refunded the money from dynomax and buy some mass loaded vinyl to see if that would take the remaining drone away.
2500 rpm was the constant drone that is now gone, and the 3000 rpm drone is when climbing a hill, and the 1500 rpm drone barely ever happens only when is about to shift into second but it doesn't and it's quiet drone. So just the 3000 rpm drone to deal with.

What do you guys think?