I had the exhaust work done yesterday and am very happy with the results. I found a local shop in Lexington Park Maryland just outside Pax River, through the stop the drone/helmholtz style thread.
http://www.camaro5.com/forums/showthread.php?t=102075
For those of you with drone issues, I recommend you read this thread. There is a lot of useful information. You can PM Roger Ramjet and he can educate you. Rusty and his crew were great to work with.
I had a set of Kooks resonators installed to bring the overall volume down. I also had a set of helmholtz pipes installed to eliminate a loud drone I picked up that seemed to center in between 1700-1800 rpm. Basically, the rpm band for cruising in 6th gear at 70-80 mph. The volume in the cabin is much lower, but the sound outside is still very aggressive. The entire cabin used to hum whenever the rpm was less than 2000. Now it is entirely gone in 1st through 5th. 6th is completely quiet except when accelerating uphill, but even then it is less than half the previous volume. Roger is confident that we can adjust the length of the tube to target the frequency. But to be honest, I was trying to make it drone. I normally would downshift in that situation. Here are some pictures that Roger provided.
First is the entire exhaust assembly. Then a close up of the Helmholtz pipes and the resonators installed on the car. The helmholtz pipes are forward facing but they sit higher than the bottom of the headers or suspension. They are also braced at the ends. I'm not sure if that is clear in the pictures. The resonators required a little modification to match up with the x-pipe and fit inside the tunnel.