i just put it in on saturday, there is like a knocking noise (like if you used a stick and hit it on a tin can) from underneath the midsection of the car.

it's loudest when the car is cold, then after its warm it makes the sound only during certain types of bumps.

otherwise, it runs and sounds great

please help! what's going on?

 

it might be an exhaust leak. My buddy's cobalt made funny noises when he had an exhaust leak.

 

so if there's a leak the exhaust vibrates more and is hitting something? but why is it worse when the car's cold, or when its bumpy?

 

It might be banging against a heat shield. Make sure that there's no heat shield within a 1/2" space from the piping. When you hit a bump, it might just be b/c the exhaust is on rubber hangers and it's swinging a bit into the shields. If so, bend the heat shields away a bit.

It'll be worse when cold b/c the engine idles at a higher rpm causing more vibration in the car and from the engine through the exhaust. It's most likely a heat shield.

 

yea its probably swinging and hitting the shield

 

thanks for the suggestions guys!
i'll check it out!

 

CHECK IN THE MIDDLE THERE IS A BRACKET RIGHT BY THE RESONATOR AND IT HIT IN MY BOX AND 2 MORE OF MY FRIENDS HAD THAT PRBLEM AND ALL WE DID WAS ROLL IT A LITTLE AND PROBLEM SOLVED WE MADE IT LOOK LIKE A LUMP JUST SO IT COULD CLEAR

 

thx that's what i did over the weekend. put some washers on the bolts too so it would give just an eensy bit more clearance. i also had the gasket from the oem exhaust on there

did you guys notice the the pipe from the cat now looks kinda low? almost seems like the bit on the greddy that connects to the pipe from the cat could be like a couple inches shorter

 

Dude! I have the greddy evo2 exhaust and i have the same damn problems!! It rattles against that little mid brace and it hangs noticably lower in that area between the center of the car and the rear axle. I was thinking myself that the design of the axleback must be too long or something. It bugs me, i might even switch exhaust, i just really like the sound tho, i dunno what to do

 

well, don't other exhausts have their own fitment problems too?

if not, then the greddy folks should listen and take notes....
it's a great exhaust but it does not fit as well as it should! i'm sure they don't want ppl reading this....

 

Yeah i have the same problem with mine. Like everyone else i just added some washers and it fixed the problem.