The 323 Outlaw Train Horn Kit builds on the 127VX feature list. The 323 features the heavy duty 325c ViAir compressor and a separate 2 gallon tank. The 325C is one of the fastest fill compressors on the market. This 150psi system will drive the chrome plated 3000 train horn to the max. We've upgraded to 1/2" air line for high air flow.