Well I should be getting my MagnaPacks soon so I took the stock catback off...and took a little video of me revving with no mufflers...thought you may enjoy.
http://s133.photobucket.com/albums/q41/XxMustang281xX/?action=view¤t=StangNoMufflers.flv
http://s133.photobucket.com/albums/q41/XxMustang281xX/?action=view¤t=StangNoMufflers.flv