Ok, to start, there is nothing wrong with the stock HHR SS 'cat-back',
exhaust system.
It is very 'free-flowing', & is not restrictive.
I've tried many different mufflers /resonators/tubing changes, & there
really isn't any power to be gained by changing the stock 'cat-back'.

So, changing the 'cat-back', or any part of it, is for a matter of taste,
or sound.
I like the stock sound, & I really didn't like any changes, that made it louder,
as I just didn't like it louder at all. Four cylinders sounds, are crappy...

So, I decided to built a 'catback' system, that was DEAD quiet.

I used a 3" 'cat-back' system, Part# 16811, to start with.
http://www.magnaflow.com/02product/s...ne=all&id=8775

Then I added the biggest 2.5" resonator, that would fit between the DP, to where
the tubing starts to bend, part# 12640 , which is 6" diameter, 27" long.
http://www.magnaflow.com/02product/s...=main&id=11610

Then I replaced the 3" ID muffler at the back, with a muffler with the same outside
dimensions, but with a smaller 2.5" ID inside tubing. Part# 12226
http://www.magnaflow.com/02product/s...=main&id=11558

To end the system, I added a stock HHR SS 'tip', so it looks stock from the rear.

I did try 3" resonators & mufflers, but they were loud, & were overkill, as 2.5" ID , are
sized right for our needs.

To get the huge resonator to fit, I had to weld the flange to it, that bolts to the DP.

I ran 12.4s at the track with the stock 'cat-back', & then ran 12.4s with this DEAD quiet,
custom exhaust 'cat-back' system.

 

'Sounds' Sexy! Nice work though in all seriousness.

 

and now the neighbors like you again!! but seriously, thanks for the time trouble and expense to bust all these catback systems and their claims to fame!!!

 

I've always wondered what the car would sound like with a dump tube bolted up to my catted DP so I want ahead and fabbed up a 3" dump pipe. It was a legit fab with hangers and all. Here is what it looked like





The very next day I took it off because it was the worst sounding car I've ever heard and it was so effin annoying. What was I thinking you ask? Like Dave, I too am not afraid to try new things to see what advantages are available, even if it is a small advantage. Nonetheless, if the hp gain would outweigh the tq loss i still wouldn't even use this for track days only. Part of the reason I did this was to see how a 3"cutout would sound and affect power. But I think even a deaf person would hate this setup lol.
Dave, now i have to STRONGLY disagree with your statement about our buggys not sounding good with some more open exhaust persuasion. After I re-installed my catback I did the muffler delete mod and I must say it sounds AMAZING with a catted DP. I too do not like the sound of most four bangers with exhaust but ours is special and carries a unique tone. I like a mellow exhaust note and this provides just that. IMO it makes the car sound quite impressive, not obnoxious or loud. But it's hardly "stealth"

 

Hey just noticed this.......

Did 2005HHRauto INITIALLY post this thread AND his thread on the rotor update on 4-24-14, or is there something wrong with the software of this forum?

I can't believe it took this long for someone to answer/respond to his postings.

 

I just updated the Ruthless-Pursuit-of-Power thread : to include these two threads, incase someone was following it...
https://www.chevyhhr.net/forums/hhr-...t-power-43170/

I just noticed that the Magnaflow links above are all screwed up...
I think Magnaflow keeps changing the correct part# links ???
Here are the correct updated links:
Magnaflow Cat-Back part# 16811
MagnaFlow Exhaust Products - For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles
Or this link, if the Magnaflow link doesn't show the right part#
http://www.summitracing.com/parts/mpe-16811
Super large resonator: part# 12640
http://www.summitracing.com/parts/mpe-12640
Rear muffler: part# 12256
http://www.summitracing.com/parts/mpe-12256
Pics of exhaust system: