The air horns are in and sound bloody great. I made a simple bracket to mount the horns just in front of the radiator, but air flow won't really be effected in any way, and the compressor was mounted under the front bumber bar on the battery side.
The real bitch was running the wires from the engine bay inside to the car. I had to request the help of the fairer sex as my hands were too large for some parts.
Anyway after some modifications on the original wiring diagram provided (the diagram and instructions were ****e as normal) I now have the dixieland theme playing through its own hidden switch and my normal car horn was never touched.
One of the best B'day presents I've have gotten yet