Exhaust Help

I didn't know where to put this so move it if need be. I need help on what muffler to put on my tow truck. I hate to say it but it's a Chevy 6.0. I don't want to try a Chevy board it would be a pain in the ass for a muffler. The truck has true duals back to a single two in one out muffler the size of a 55 gallon drum. I am wondering if I should duel it all the way out or go two in, one out cat back. I dont want it to loud. But I would like a good sound. My biggest consern is cab noise and something high pitched. I was thinking about dualing it with Dynomax ovals. Or putting on one or two flowmasters. But Flowmaster makes like 7 types now and I dont know which one. Do you all mind helping?

the dynomax ovals are LOUD as are the round ones. Gow ith the dynomax race magnums. They are fantastic sound good and very durable.