Sorry I can't help with info like that; but I must say I am very impressed with the horn on my car. Sounds good to me and much louder than any other car I own (except those with air horns I will admit!).
The wiring will not be a problem, physically fittinga traditional air horn and compressorin will be.
If you can find the space to mount a compressor and the horns just use the feed from the existing horn to trigger a relay for the compressor. If you want you can also fit a switch to swap between the two types of horn.
You might be better off with something like a Stebel Nautilus.