Hello,
Sorry to post this basic question, but can't find anywhere for sure on this site or net.
What is the size or diameter of the factory downpipe on a 2009 Cobalt SS ?
Thanks.

 

3", with a slight reduction between the cats where the o2 sensor sits.

 

If you want a catless one go zzp. Just got mine on it sounds sweet

 

I'm thinking there is somewhere that it necks down to 2 1/2 briefly verses the aftermarket ones being 3" all the way.

 

Thanks. And then stock is 2.5" right after the downpipe ?

 

I swear it was 3" all the way except where it squeezed down for the o2 sensor to clear, and where it necked down to 2.5" was on the outlet of the resonator. I had bought my MPx exhaust before Omiotek made my downpipe for me and the 3" pipe looked the same as the cat outlet. I may be mistaken, but I swear I'm right lol.



Yes, the stock exhaust after the cat is 2.5", the aftermarkets are 3" from the cat all the way back.

 

Good call on your downpipe maker and I love my mpx exhaust. I wish I still had my stock downpipe I would go measure it. I have a ZZP catted one out in the garage and I remember comparing the 2 and was thinking there was difference in id on the ZZP compared to the stocker in one part of it.

 

Would the ZZP catted downpipe be for sale ?

 

Stock do is 3 inch all the way except for the o2 part like u said. I have one in my shop if someone don't believe u lol

 

I have a careless downpipe with no second 02 ready to ship. Ships from Canada though

 

If you want the catted version with angled defouler shipped from CO just PM me. Looking to reduce some parts I have laying around.

 

Just measured my factory exhaust on my 09 SS. Downpipe is 3" and right after that from the resonator on right out the back is 2 1/2".