Well, my '78 K-10 is running full length headers and 2-1/2" true duals with Cherry Bombs, dumping at 45 deg down turns just behind the rear axle... Old school snotty sound for sure ( I call that truck the Pissy-*b-word)... But probably not what you are looking for..
On a past truck I had, (an '01 Silverado) I bought a Flowmaster cat-back system with a 40 muffler. It sounded good and wasn't overpowering going down the road. Installation is a piece of cake (so long as you can get the y-pipe flange nuts loose on your stock system) but the drawback was short service life here in the salt belt... I think it was only 2 or 3 years before the first holes rotted through on the muffler and once that occurred it was only a few months and the rest of the system just went right to hell...
If you are in the salt belt I would recommend spending the coin on a stainless system if you want it to last more than 3 or 4 years.....