After I drive the car and turn her off, I hear a weird popping or cracking (not crackling). It sounds like what you would expect due to exhaust expansion except it is much much louder and more pronounced.

I have the stock exhaust on my 2003 5AT sedan. any help greatly appreciated

 

check for exhaust leak; it is very common in aftermarket exhaust, but in your case with your stock exhaust, I would wanna check if sth is leaking.. or maybe sth is banging against sth (since when u turn your car off, it is just like accelerating, you are indeed putting load on the exhaust system through the movement of the engine. For instance, someone with a coupe middy may experience its middy banging onto the driveshaft retainer during the engine shutoff...)

Good luck in finding out the exact problem

 

its not your car just warming down?

 

i would think it was just the cool down, but it is way louder than what you would expect from that and goes on for quite some time, might be a little rock stock somewhere

 

i got the same problem,i just think maybe its the honeycomb thing breaking loose

 

finally. where is the "honeycomb" thing?

 

Did you ever figure out what was wrong with the car I have a 03 5at it has the cracking sounds from underneath

 

Take it to an exhaust shop for a diagnosis.

 

Cleric I’ve brought it to 2 exhaust shops and another mechanic shop they all say it is normal cool down but there’s no way it’s normal if it’s doing it while the car is running and at idle.. it’s happening after driving it for 45 to an hour the I open the door and here crackling popping ticking noise coming from somewhere towards the back of the y pipe ..

 

Does it sound just like that metal expansion sound you hear when the exhaust is cooling down?

There's a chance you lost some of the catalytic converter element that blew down the pipe and is loose inside the resonator or something. Unbolt the midpipe and shake out the resonator to see if there's anything in it. Better yet get rid of the sedan OEM midpipe and put the coupe midpipe in it's place. Makes the sedan sound a LOT better.

I'm guessing this sound is persistent at idle as well yes? If it only makes the sound when driving but NOT at idle I would suspect some piece of road debris or piece of tumbleweed is lodged into something.

I had a tiny piece of a tumbleweed lodged under my car (literally the diameter of a toothpick and about 6 inches long) that was stuck in the chassis and just barely touching the ground and it literally sounded EXACTLY like there was a plastic bag dragging under the car at city-driving speed.