A bit of an eyesore...rust on the exhaust tips and the underbody of the muffler.
Can this be taken off with rust remover or a wire brush?
Any other trick beside buying a new muffler?
Are you sure that the muffler is rusting - I thought all standard mufflers were stainless steel! Mine is - no sign of any surface rust after 8 years.
Could it be the corrosion protection fluid that has been applied to the cars underside that looks like rust....
for light surface rust/corrosion you can try a household cleaning product called "Bar Keepers Friend" or as mentioned above a scotch pad or even an SOS pad. For heavy corrosion you may need to break out the wire brush or dremel and polish it up completely.