Brian is correct except that a 2003/4 muffler will also fit.
http://www.renntech.org/forums/index.php?showtopic=989&st=0&#entry4301
Ian in the UK with a 2000 put on a rear bumper from a 2003. He like the way it looked so then he put on a 2003 muffler. The muffler came long after the bumper cover.