AudiForums.com - HELP - 2.0T with crackling noise from underside

Hi...

I am looking for some assistance to those that has Audi with 2.0T engine system (A3, A4, A5 or Q5). I purchased a 2012 A5 2.0T last year and has been battling a crackling sound that you can hear when the engine is idled or at a stop with engine running. I found two sound files recorded by others so you guys can hear it:

audi a5 noise.wmv - YouTube

2010 A4 with weird buzzing noise from underside of it. - YouTube

This sound does not occur at cold start...you have to drive the car for a 10-15 min (possibly with highway driving) and get the engine hot. Then you can either just stop the car with your foot on the brake or completely stop the car by putting it in "P". Roll down your window (turn off your radio) and you should be able to hear it from inside the car.

I've been to the dealers at least 4-5 times to get this noise eliminated. I've gotten answers ranging from:
- can't duplicate
- muffler loose, so we tighten it up
- replaced middle muffler with a new one
- the latest - it's condensation inside the middle muffler that's causing the sound and there's nothing they can do about it.

I've personally have also heard this same sound on the A4 rental they gave me. and with the two sound files above, it looks like both A4 and A5 have this sound. The dealership also acknowledge that they can hear this sound with one of the A5 they have on the lot.

They told me that there is nothing they can do to fix this because this is cause by Audi designing a middle muffler in the exhaust system. The dealer also told me that i can eliminate this sound by installing the Stasis exhaust upgrade, which would completely eliminating the middle muffler. However i will have to pay ~$2000 to get this done.

I am asking to all of you to:
- If you have an audi with 2.0T engine - do you also hear this? I think most people does not hear because in normal operation, you shut the engine down almost instanteneously or you'll have the radio on when you go thru a drivethru for example. I would appreciate any feedback if you hear this sound.

- I am also asking to those who are more mechanically inclined, is the "condensation in mid-muffler explanation" makes sense? to me, the sound is more of a heating/cooling metal expansion/contraction...doesn't sound like a liquid evaporating...Please advise.

I would appreciate any feedback anyone can help me with.