BBK makes a muffler? News to me. I'm fairly certain the Magnaflow is the most quiet bolt-on axle-back exhaust available to the 4th Gen F-Bodies.
Just to be certain, take a look under your rear bumper to see what it says on the muffler. This is a good deal on a Magnaflow system for sale here by a club member:
http://www.njfboa.org/forums/showthread.php?t=55511
The swap could be done yourself for free, or for under $100 at most any shop.