Weird Buzz sound when engine is cold

[FAST RS]

About 2 days ago I turned on my car in the morning and heard a scraping / buzzing sound coming from the engine for about 5 seconds and it went away, this morning and afternoon the same thing happened after the car sat for a few hours and only for a few seconds. I also noticed an odd sound under the car when I am driving almost like a clink when I accelerate. I did put a Flowmaster catback on 3 weeks ago and am wondering if this is the issue before I take it to the dealer. Any suggestions would be great. The next time it happens I will try to capture it on video.

[DallasRT]

The Hemi is just a noisy engine. Ive noticed mine has been a little louder in the cold lately. If you do a search you can find several threads on different noises people have heard. Your description kind of sounds like mine which is normal apparently. As for the clunk, mine does that if I'm in autostick and I let the car shift down for me. I'm not sure if yours is A5 or M6 but thats what it could be.

[FAST RS]

Found the problem, 1 of the mufflers shifted and is slightly rubbing against 1 of the bolts on the drive shaft, I will be going back to the exhaust shop tomorrow.

[Hell Ride]

Yeah that'd do it lol