Ok, muffler one more time!
 

The 2.4L HHR stock muffler is not a straight through muffler. From the pictures of it found on this forum you can actually see it's quite restrictive in comparison to a straight through muffler.

But as I'm sure most of you guys know, a straight through muffler is going to be very loud.

Here is what I have been trying to accomplish and what has happened so far...

stock muffler = Baseline
K&N intake = More engine roar
Dynomax super turbo = drone
GMPP/Borla cat back = drone
Dynomax VT = almost perfect
sound deadening rear of vehicle = a little closer

Since I paid for the Borla cat back already I didn't really want to cut into it, so swapping the mufflers is what I have tried so far.

The Dynomax VT is awesome and I recommend it to anyone that has an HHR as it's all the performance without the loudness and the drone except when you want it. I would say the only downside is the rattling valve at idle. And it seems they stopped making that particular muffler.

The reason I would like to quiet it down more is because I drive up long hills everyday now, during those times the valve or RPMs or whatever causes it to be at it's loudest. (Which may actually not bother many people, but I would say I have sensitive ears I guess) I want it to be a nice sounding muffler that's quiet inside and mean outside or just a little rumble over stock.

I am hoping you guys can tell me what you have done or if there is a muffler out there that is not as restrictive as stock and still has a quiet volume?

My next idea was to cut the valve out of the dynomax VT muffler since it works so well and weld it on the back of the longest magnaflow I can fit in the back. I figure this would work since the muffler size area in the actual VT muffler is 2/3 pipe and glass (things that would actually quiet the exhaust gasses) and 1/3 pipe with a valve in it(no added quieting material except for the valve), so technically the actual muffler part is quiet small internally.

Thanks for the advise in advance, if there is anybody hiding on here that has that awesome set up, please share, I mean I have seen another HHR that had flames in the front and a fake supercharger glued to the hood that had a nice muffler that was very quiet but you could tell it sounded like it had a little muscle to the car, I just couldn't run fast enough. lol so if your on here what do you have under there???

From my understanding I dont think the exhaust system is very restrictive to begin with? The car doesn't sound TOO bad stock, IMHO. Here's Gregg for comparison, revving to 4 grand due to the limiter in Park.

Stock isn't as restrictive as you think... It's heavy and ugly but works well for what it is.

We just went to the Walker 2 1/4 inch system , it has a longer resonator and doesn't drone at highway speeds. It doesn't really growl either. The HHR has the K&N FIPK intake

We just replaced the meek 1 3/4 exhaust in Sweetie's Sunfire GT, it had 2 inch exhaust and two mufflers from the factory, it was replaced several years ago on the cheap with the single system.
Jesse a muffler shop friend of mine dabbed up a 2" cat back with an 18" resonator that splits to two Flowmaster mufflers, it has a purr at idle then a growl whilst accelerating and no drone on the highway.

Is it just sound or does 1/2 a horsepower mean something to you?

If it's HP why not worry about the water pump, A/C, balance shafts and alternator?

I'm sure someone has dyno reports to show just how much each of those use. I'd bet more that a muffler.

https://www.chevyhhr.net/gallery/fil...rtlegutted.jpg
Well this looks restrictive. From post 9 of this thread:
https://www.chevyhhr.net/forums/mods...picture-53081/

And yes, I put the K&N intake on there for ease of access to get to the filter, make the engine compartment look a little more performance looking and hear the engine a little more.

The muffler was well... Yeah it's great to have a little performance increase but I like to have my car sound like it's meaner than the next but not in any way where you wouldn't want to drive it on long trips.

This I the only car I have had this problem with, I am usually able to put a turbo style muffler on any car and it only be slightly louder than stock, which is what I was going for. For some reason maybe because it is a hatch back style car and doesn't have that trunk area to stop the sound, it is much louder???

By looking at the above picture would you say that the stock muffler is more restrictive than the walker replacement which claims tri-flow?

Aradmahogany, I don't know if you have the straight through version of our stock muffler that I guess came with a manual transmission?, but I don't think mine ever sounded like that.

Ok, since nobody is shooting out any ideas, I thought of one more that I had.

Right where the down pipe passes the cat and turns back, there is a nice spot to add a round muffler in the front before the resonator or flange connection.

If I put a round straight through muffler there, wouldn't it quiet it down quite a bit? And if so I could even have the exhaust guy slip on a long magnaflow in the back to see if there is no longer a need for the valve in the VT muffler.

If my idea is correct, it should be quiet, free flowing, and no more valve rattling, right?

The exhaust would then be quieted down by the cat, then a magnaflow, then a resonator, then another magnaflow. All the while not ruining the GMPP catback.

Sounds like you want to use a 2010 exhaust; 2 cats and a resonator.

Attachment 21888

This is a Walker Quiet Flow; it looks way more restrictive to me.

Attachment 21889