Any thoughts on what might be wrong with this bike...?

Just FYI polishadam82 is the current owner, I offered to help with the bike and issues and he declined.

Maybe the new owner bought it thinking the "rattle" would be an easy fix and he could keep or flip. Then he discovered it has a serious problem and decided to bail on it and get his money back or even make a little. Hoping to find someone like himself who thinks it's an easy fix. :-?

One thing is if the pipes look stock someone may have tried drilling them out which might cause some decel popping.