I welded a 3" round tip directly on the glasspack for the exhaust on my Demon......When you looked into the tip, you saw a "double" outlet....sounded good, and really took the bite out of the Magnaflows that were on it.
This same basic set-up worked great on the Dart Sport. It deepens the sound, and removes any raspy hollow tinny sound that it might have with chambered mufflers.