I just need to know the cobalt SS s/c's stock exhaust diameter. I'm pretty sure it's 2.5 but I need to know...gonna buy the quicktime electric exhaust cutout with the y-pipe. Thanks!

 

2.5 until it gets to the axle, then it turns into 2.25

 

so if i get a cat-back exhaust does it start at the downpipe since the cat is in the downpipe or does the downpipe have to get sawed into?

 

It goes from down pipe back.

 

I thought I read on a GM site that the majority of the exhaust is 2.25".

 

2 1/2" at cat conv connection--2 5/8" pipe going into cat conv--2 3/4" downpipe after cat conv--necks down to 2 1/4" at resonator connection and 2 1/4" coming out of resonator--then goes into 2 1/2" for section that crosses under the car toward the driver's side--makes curve at driver's side, necks down to 2 3/8", into 2 1/4" all the way into the muffler--coming out of the muffler at 2 1/2" into 3" exhaust tip.

Doc

 

wow.... ok everyone stop posting on this topic lol he just owned everyone (if he was rite, which i hope he is cause i aint checking)

 

now, youre talking id, right?

 

using a caliper as accurately/tightly as I could. That is the standard (OD) most muffler shops use. As a matter of fact, the measurements of 2 1/4" & 2 1/2" were right on with some pieces of sample exhaust pipe I have from a muffler shop and compared them to. I think the exhaust tip inside diameter measured 3". The GMPP angle cut exhaust tip is 3 1/2" ID and 4" OD.

Doc