The muffler or catback kits are really just going to be for sound, so I would just pick what you think sounds nice or looks nice if you go with a catback with larger tips. I prefer the Magnaflow catback system myself, but the Borla and MBRP are very nice as well. If you just want simple and less expensive, then you can also go with 1 of the Mufflex bolt on Magnaflow muffler kits. These are only $289, and you have the option of running a 14", 18", or 24" muffler. The shorter the muffler, the louder it will be.
The real power gains are going to come from longtube headers. Best system out there is going to be the ARH 1 3/4" with high flow cats. Fitment is perfect, its all mandrel bent 304 stainless steel, Comes with plug-n-play o2 extensions, gaskets, bolts, and clamps, and going with the high flow cats is going to prevent the truck from being obnoxiously loud.
