I have a custom cat back exhaust from RDP which I love.
I have two crappy vids here -
Index of /movies/RedcliffeDyno
But I will take more in a couple of weeks when I get home. I found the MDS didn't make a huge difference with mine just a bit of a change of note.
Cruising along it is not loud in the cabin....does get pretty loud around the 100-110kmph mark but then quietens again. Unfortuantly I haven't had a chance to hear it roar from the outside but I have been told it sounds great.
Here are a couple of vids from out side of my car where you can hear the exhaust.
YouTube - 300c 5.7 at willowbank Raceway
YouTube - ohnoes300c's Channel - Click on the one called
2006 300C V8 Hemi - Pusbum 279.8 rwhp