Have it on the car for a year and a half.
For about half a year now, the damn thing makes crazy noises when you shift hard or start from first. I tried adjusting the hangers and nothing seems to fix it.

What can I do?

 

wow, that sucks. Have you tried putting bigger stiffer rubber bushings on the hangers to hold it in place better?

 

No, should I just buy replacements from GM? Or does a parts shop sell something that will fit the factory setup?

 

Did you install the GMPP exhaust or have it installed after you bought your Cobalt -- if yes then it was only warranted for a year. If GM installed the GMPP exhaust before you took delivery then it would be under your Cobalt's warranty.

I had a rattle in my GMPP touring and they replaced it under warranty. It would rattle at idle and when accelerating when hot -- but when it was cold it wouldn't rattle.

 

I had my mechanic install it about a year and a half ago. Also, my car has 40,000 miles so it is no longer covered by the warranty

 

Drat! Replacement time.... Does it sound like it's the muffler? If so you could just get that replaced with a stainless steel aftermarket muffler -- probably the least expensive route.

 

yeah, mine just started a day or two ago. Can't find the exact spot yet though. Seems to be when its hot only though.

 

Check the heat shields. A couple sections of heat shield were banging against the exhaust.

 

you should be able to take it to an exhaust shop and they could replace the "wore out" bushing on the hangers with stiffer ones and that SHOULD stop the rattling. Hopefully. And it shouldn't be but a few bucks.

 

Quick way to check the bushings is to lube them -- if it's the bushings they'll be quiet. Mine turned out to be internal -- coming from the muffler.

 

What header do you have? Mine made the same noise, but turned out to be my flex pipe rattling against the frame, due to the bushings be worn. Got new ones from a local shop, and bam rattle gone!

 

stock

 

its the heat shield under the header it happened to me... just remove it

 

Could be a few places... Best bet it to get the rear end in the air on ramps etc... and have someone give it some gas while your listen under the car for the exact spot.

 

check your heat shield

 

a hanger might be pooched and you are hearing your exhaust bang around..
Happened to me, check it out.
Ive had my GMPP performance for almost 2 years, no issues other than one (factory) hanger.

 

hold a hose or something to your ear. that'll help pinpoint where the noise is coming from. while you're at it snug all header studs, and flange bolts. check all welds to be sure of no cracks.

 

Took it to my mechanic and they adjusted the whole thing…it’s not as bad anymore but still there. This sucks! I need to buy new rubber hangers and replace them to see if that helps

 

Where are you getting the rubber hangers? Mine just started after I got rear ended...

 

jbp performance has poly hangers get thoses ftw