Removing the old exhaust started off fairly easily, but as usual, the last 2 nuts were problematic. Of course, they were the most difficult to get to. one had rounded shoulders, but a device called a "Gripper socket" soon put paid to that.
Then there was 1.
Irwin Gripper socket
This too seemed to have rounded shoulders but was almost completly round, gripper couldn't get a hold. With considerable jiggling, it came loose and was eventually withdrawn. It turned out to be a socket screw. So there you are, Exhaust off.