I figure when replacing the mufflers, the rubber hangers need replaced - hence I buy new.
My special tool is an old srew driver, slot preffered.
I pull the old off, and if they fight, I cut them. Hangers removed.
To puyt the new on, I don't worry much about streching them too far, as they are "new". With that said, I use the slotted screw driver to "pry" them back on. A philips head slips off too easily.
At about $1 each - I'm a spend thrift.
Thanks for the question.