There are several products out there it mainly matters what tone you want and I'd encourage doing your research on YouTube to hear what each exhaust tone sounds like from the different brands. I've had Flowmasters (40 series) for years on many different vehicles and love it. It's got a nice rumble to it at idle and cruising speeds but mash the pedal to the floor and it really screams. With that said, a lot of people don't like 'em because of the drone it can produce inside the vehicle. A lot of people also like Magnaflow exhaust (which I may give a try on my 07 Burb when it comes that time) because it's supposed to produce less drone and have a cleaner note to it. Then you have several other brands out there that are just as good or better but may not be as popular due to price of the muffler. You'll get claims that one flows better than another and there is some truth to it but for the most part the HP gains between brands is about the same on a largely stock motor.
I can't remember what motor you have in your rig but if I was you I'd go to YouTube and search by your motor size and exhaust or muffler (i.e. 5.3 Exhaust) or something like that. That way you know exactly what you're getting and what it'll sound like.
Just my .02 cents on the subject and hopefully it helps a little bit at least