Welcome to the neighborhood.
What year model truck do you have. On a vehicle with catalytic converters you can't just straight pipe it from the manifolds, you can behind the cats thought. The easiest way to do this, (and you may want to check local laws because removing the muffler may get you in trouble.) but you can take it to a muffler shop and have them remove the muffler weld in a patch pipe. Done, louder exhaust.
Now, for better sound that you would probably like, but that wouldn't have annoying drone at highway speeds, etc Putting a Magnaflow in place of the stock set up would give you aggressive sound under wide open throttle without driving you absolutely nuts when cruising down the highway.
Hope this helps a little