I ended up going with a 4-trumpet horn from Vixen (VXH4114B). I went for something a bit different than most, because "that's the way we roll". -Ended up going with something with a more 'musical' tone. I mounted them in a down-firing position on the passenger side near the front bumper. To make the project simple, I just wired the solenoid of the new horn into the stock horn's harness with a 12v relay.
At robbyr's suggestion, I added a secondary air tank with pressure-protection valve so that, should a problem arise with my workmanship, I will still have air for my brakes/suspension. I also took the opportunity to add in a service air port w/ regulator so I can fill my tires etc.
Honestly, the horn that came with mine was so quiet; it was as much as safety issue as it was wanting a big horn. On at least two occasions, I recall, I needed someone to notice me and the stock horn failed to get their attention. -No longer a problem...