Summer 2009: Train Horn Added - Siege Engineering "Kong II" Triple Train Horn. All 1/2" airlines & fittings, 5 Gallons tank (with 8 X 1/2" ports). Viair 480c compressor 200psi. Here's the 5 Gallons tank in the bed. There's a pressure gauge mounted directly on the tank a sensor for an electronic pressure gauge installed in the cab.