They will not sell muffler only, i tried for my last truck when they did not make a cat back kit i said i will just take a muffler and make it work and they will not sell. They claim that the wrong placement can cause drone and each system is tuned specificaly for each truck. They do not want there name on a system that is improperly installed. Thats the story they gave me anyways when i called direct down to corsa.
I had a Corsa cat back on my Denali. I chose the "sport" option and it was louder than I wanted. I called a guy at Corsa and he "allowed" me to buy the "touring" muffler for $325. Sounded sooo much better to me and if I could find a way to get that exact sound on my Hemi, I'd do it in an instant.
Funny, both were straight through styles with dome holes along the way, but one was obnoxious and one not.
On the highway it is quite as stock, Driving around town you can hear it but its a nice exhaust tone and not a deep drone. I am very happy with my choice as i pull a trailer and it will not be annoying. On hard acceleration my intake is louder then my exhaust in the cab.