Walker and Bosal are both good, but are essentially stock replacements, not performance mufflers. They might also be your only stock replacement options as parts for these trucks are getting hard to find...and don't even waste your time with the dealer because everything is discontinued as far as the exhaust. Magnaflow and Flowmaster are custom options, so you may want to consult with a custom exhaust shop to fabricate a system for you if you want to go with either of those options.