Exhaust Rattle At Idle

[B33R]

Ive been experiencing an exhaust rattle for a few months now. I thought i might have bottomed out on something and it knocked a bracket loose and either the heat shield was rattling or maybe one of the rubber brackets came loose and the exhaust was sitting on the metal mount. I put the car up on the lift and did an inspection and everything looked in order. did some research but when i searched all I got was stuff about the vanos seals. if it were the vanos seals wouldnt the noise be coming from the engine bay? i have a small rattle in the engine bay but that was in the winter and i believe it was just due to the oil not getting up the valves for a few minutes and that was the rattling. the exhaust rattle is ONLY at idle. sometimes its more of a squeal (sounds like a belt squeal with a small rattle) and sometimes its just a rattle with a drone like sound every few seconds. its always coming from the middle of the car. any help would be greatly appreciated.

[Bimmer330i]

Have you tried gettting up in under the car and shaking the pipes to see if you can pin point the location of the rattle? Bear in mind to let them cool first