I LOVED the sound of my old CB750 with the un-baffeled MAC 4 into 1.
When I cut the cannon off completely and just ran a open shorty pipe it sounded like a F1 car on decell.
If I were you I would look into making your own baffle to control the sound you want/don't want..
Something as simple as a piece of metal, then drilling holes in it until you get the volume you want might do the trick for ya !