Dry ice on the male end, mapp gas on the female. Let the dry ice sit on it for about 20 minutes. AutoZone or the like will have a tail pipe expander for loan but be careful not to go too big. Check out YouTube for guidance. If you aren't comfortable with the above take it to a muffler shop.
I dunno if I'd try anti seize. Maybe some WD 40.
If I was gonna try sand paper id use some emory cloth and tear a long thin strip, then wrap it around the male side 1.5 times and pull each end back and forth. This way you remove the same amount of material evenly. Just do a little at a time then try the fit until it goes on. It should be a tight fit anyway. Are you putting enough elbow grease on it when you try?
Last edited by fig; 08-16-2016 at 10:31 PM.