You will need to find a place to put the trumpets, tank and the compressor. Aside from that pretty straight forward. There are other louder (not louder than the train horn) horns that probably wouldn't take up as much space and would be considerably cheaper, such as the Wolo Bad Boy.
Or grab an 12v electric marine unit from a boat yard/wrecker if you can. They are not train horn loud but are pretty much semi truck loud and without the compressor/lines/tank complexity.
I've got a dual trumpet chrome unit that I'd love to fit to my machine, but finding a good spot where it's not hanging out ready to get stripped by a tree branch, or not be right behind my head, is proving to be a challenge.
Got my auto horn behind grille in front of radiator pointing down, sometimes it gets water in it on a wet day and not very loud but always dries out lol. I am thinking about a more serious horn tho.........
I have an old auto snail type horn that I may end up installing in the similar location....it's better than nothing fer sure. The ability to get the attention of riding buddies is a good thing. Whether it's because their cooler lid isn't fastened and the contents are spilling out onto the trail, or warning them of road traffic coming up behind, etc, etc. Yelling and waving doesn't cut it.
I just think louder is better as these machines are pretty noisy.
I'm also thinking about turn signals for this winter....there is a bit of road running around my place on well travelled asphalt and once the full doors go on, hand signals become almost impossible/effective.