These are the pictures of my horn setup. Could do with a little tidying up when I find the time. The horns are stacked one below the other and the bottom horn is barely visible. I have used twin FISA horns. They have connectors for 12V+ and earth through their mounting bolt and brackets. I made the wire with the connectors for the 12V+, then threaded it through the fuse box before connecting on the 'add a fuse'. There are now two horns under the bonnet as well as the original factory horn under the front bumper. You can see the 'add a fuse' in the fuse box.