Gutting 2nd cat
 

Before everyone jumps on me and says click the search button that option does not work well at all on my phone. With that being said has anyone gutted their second catalytic converter and left the stock muffler? If so can someone please post a video or sound clip please? I cannot find an aftermarket muffler that I like the sound and everyone keeps telling me to just gut the converter to make it louder and free up horsepower. I'm just curious as to what it would sound like. Thanks in advance

I don't know why the search would be different on a phone. But, here is a lengthy discussion.
https://www.chevyhhr.net/forums/hhr-...2nd-cat-49887/

From my iPhone

https://www.chevyhhr.net/forums/esp_...nd+cat&type=vb

Yes I did ....worked like Dave said.:smile:

I just noticed that you don't have an HHR SS so I don't know if modding the 2nd cat will work for you.
The 1st & or the 2nd cat could be restrictive on a 2.2/2.4 HHR.
Maybe a larger diameter aftermarket DP might be the way to go, I really don't know...
Do a search on exhaust mods for the 2.2/2.4 engine.

Of all the catalytic converters I've gutted (3 or 4 I guess) I've never left anything inside when I'm done. I used a solid steel rod that was maybe an inch or so in diameter and a B.F.H. (Big ___ Hammer) You just get the cat on the floor, stick the steel rod into the inlet and start hammering away...the "guts" fall out the outlet...you might reverse the direction of attack a time or two, but that's how I've always done it...never looked at the cat/cats on my 2.4 though so maybe something is different.
The better way of doing that though is buy an aftermarket low restriction cat...Walker used to make a really good one...
On my Corvette I removed the pre-cats and installed the Walker low restriction converter, then ran the rest of the way through Lawrence Keech Side Pipes...that set up was good for 40+ HP on the dyno

Get a ZZP shorty header and catless downpipe. Sounds great with stock catback.