Back when I had my 2.2, I had a ZZP 2.5 inch downpipe with 400 cell cat, and the FACTORY catback from a 2.4 Cobalt(same as 2.4 HHR, but a bit longer tail pipe. Also same as 2.0s/c Cobalt). Had a nice, deep, throaty sound, without being obnoxiously loud, with almost no drone at highway speed.

 

Well guys, I can happily say I am finally done!

I ended up keeping the borla cat back system, but removed the muffler.

The muffler that finally worked is...

The Dynomax VT 17159 muffler, the one with the valve inside it.

It's perfect, quiet, no drone, and sounds awesome when you put your foot into it, and the performance is the same, it's beautiful.

The borla sound is more drone when you put your foot into it, but the dynomax is that old school v8 rumble. :)

Finally, if you have a 2.4L HHR get this muffler, for that awesome sound and added performance, with no drone, and lifetime warranty!

 

And so are you selling the Borla muffler? Post up a for sale ad!

 

Well, I cut the tip off, so it still looks like I have a full borla cat-back. :)

So I don't know if anyone would want it, it's all there though, hangars and everything, just no tip.

 

Start a thread in the classifieds with pictures and a price!

 

Just installed the ZZP full length header and 2.5" catted downpipe to go with the borla/gmpp cat back. Sounds great, has a nice low growl to it now. I have a lot of driving to do and will break it in this week.

 

Nice, it just didn't work out for me, but now I'm happy. And the performance is all there! You can't even feel the shifts anymore, and there is no hesitation at all.

When I put on the intake, the car seemed to act a little funny, but now...

It's like I gave it more air to breath with the intake, but no where to escape.

But with the exhaust it's perfect.

 

you should try to post a video or audio clip of it

 

Yeah, no problem.

Here is what I have so far:

http://gio-outdoors.blogspot.com/200...bsite-use.html

 

Just drove 266 miles in the texas hill country on 2 lane highways at 75 mph and got 32.8 mpg. I love how it sounds now, it's not quiet, but not obnoxious at all. New exhaust, new lowered suspension, new ttr sway bar, that was a fun trip. I love this lil trucklet.