At night, shine a flashlight into your HHR SS muffler, & count how many rows of sound supressing "holes" that it has...

I'm thinking that there must be 2 different mufflers, manual = 4 rows, & automatic = 12 rows.

I have 2008 & 2009 HHR SS automatic mufflers, both with 12 rows.
I have one 2008 HHR SS manual muffler with only 4 rows...

I can't belive that GM would do something this silly...

Straight threw muffler internal piping = 2.75"
Internal piping is tightly wrapped with 1/2" thick 304 stainless wool.
Muffler "can" has "fiber" fill for sound control in 2 large "pouches".
Muffler "can" is irregular shaped to maximize size in the space it's in.
It's a well thought out muffler, that flows very well...
Click on pics to enlarge photo:


Oh ya, muffler weight with tip = 16LB , just the internal pipe w/tip, as shown in the pic = 5LB
A 304 stainless muffler "replacement" pipe that I made with no tip = 6LB

So you can do a muffler "delete" with a piece of piping & save 10LB...