2005 4.4 Exhaust vibration/noise *New Member

[tmpE86]

Hi, about a month ago I traded in my perfect Z4 coupe for an 2005 X5 4.4i, 84k miles. Had a bunch of problems, I didn't test drive/check over the vehicle enough at ALL, had way too much trust in my local BMW dealership. I had an exhaust leak by the muffler, which they repaired, but only after trying to force me to believe the noise was 'normal'.
I am worried I still may have an exhaust problem, basically between 1800 and 2500 rpms the exhaust seems to 'groan' or 'hum', very deep sound. It does this through every gear, and I can feel vibrations through my feet, but once past about 2.5k it smooths out. In 6th gear, this exhaust noise is loudest at 60mph(about 2k rpms). Happens only under load and is the noise seems the be from below my feet or closer to the engine. I don't really hear an exhaust leak with the windows down. I have looked over the exhaust system, no signs of a leak, but I couldn't see the manifolds or the top of the pipes that well. This is the only X5 I have ever driven, and I read how people say the X5 is soo quiet, I just can't believe this is their definition of quiet? Could bad engine/exhaust mounts be bringing this noise and vibration in the cabin? This can't really be diagnosed over the internet, but a simple normal or not normal, maybe some places to start looking, would be very helpful.