[ame=http://www.camaro5.com/forums/showthread.php?t=102075]Stop the Drone - Helmholtz Style - 2011 Camaro ZL1 Camaro Forum / Camaro SS and V6 Forums - Camaro5.com[/ame]
It works, and as far as I know a mustang guy tried it first and now more people are following.
Here is the original thread.
Exhaust Drone is Completely Gone - Ford Mustang Forums : Corral.net Mustang Forum
Here is where I did it myself.
http://www.svtperformance.com/forums/exhaust-215/742329-drone-question.html
It worked really well on the G8's when the AFM would kick in and start buzzing down the highway...