C. Hart

I have seen different people in different places post different sizes of exhaust as stock for my 2014 Sierra L83. Some say 2.5 some say 2.75. I am considering replacing the muffler with a Dynomax Super Turbo, perhaps 17739. I had the factory L83 5.3 replaced with another L83 5.3 from Jasper Engines. I also put new Walker Cat / Y pipe on. I would appreciate opinions suggestions about what would be a good muffler setup. My main interest is a low rumble and the best flow / fuel mileage I can get. Not interested in straight through glass packs or loud exhaust. Those days are way behind me now. Thanks Guys.