diesel mufflers

i've seen some guys running a diesel muffler on there trucks.Is this a performance thing or a way to correct drone or both.Im curious because my truck has horible drone at certain rpms and i wont to correct this.I have shorties with no cats and a 40's flowmaster dumped before the axel.I have a 3" in and 2 2 1/2 out 40 series that i want to put on and run the tails out to each corner up high and turn them down where you cant see them.would i be wasting my time.dont get me wrong it sounds good 75% of the time,but the 25% makes me want my cats back.also im getting ready to put my cam and converter in and dont want it to sound like guano.

no cats and dumped before axle is your problem i think.. my droned real bad before i had it turned out in front of the tire. you need to exit somewhere other than the ground. Just from personal experience...