I guess if it was me I'd look around at videos/sound clips until I found a sound I liked and go with it. I know Flowmaster has options for the 6.2, don't know what other exhaust makers offer but I'm sure somebody makes something with a sound that will suit your wants.
Make sure to double check your warranty info to make sure you're not voiding anything before you do a whole system at an exhaust shop.
I agree, when I wanted something I found some makes & models and hopped onto YouTube and listened to the same engines with the muffler I was interested in.