Was looking at the to-do list in the garage yesterday and decided to tackle the "whats making that rattling noise?" line item. Jacked Mazikeen up on the passenger side and laid under there to try to find the source and think I've got it.
Appears the cats are starting to come apart, or something was accidentally dropped down into the piping where it connects to the downpipe. Either way, seems like this will need to come off for further inspection, in which case might as well get the LSD out of the way as well!