Whats the best way to get the orange rust out of my exhaust pipe?

I have about a two year old subaru liberty and this orange rust is starting to form on the inside of exhaust pipe. Whats the best way to remove this?

Whats the best way to get the orange rust out of my exhaust pipe?
Dont worry about it, you are not going to be able to remove it on a permanent basis, after all, its a exhaust pipe.