I was just surfing around and found this. I think this guy has been into the crack-binge lately. Down in the post it says people can't run aftermarket exhausts without the Cat-Converter. Riiiiight. :scratch.
http://hayabusa.org/cgi-bin/busa/ikonboard.cgi?act=ST;f=6;t=71012
http://hayabusa.org/cgi-bin/busa/ikonboard.cgi?act=ST;f=6;t=71012