Nice work, Docc.
My approach was similar, but I located 'em where I figure they're more of a straight shot at the target (see post 45 from 4 years ago).
Being highly suspicious of most everything I encounter within striking distance of the road that isn't stationary, and having experienced more close calls than I can remember, I was after the most direct way to get the full 135 db of a matched set of Fiamm Highway Blasters as directly as possible into the tympanic membranes of the most severely brain dead traffic slugs I'm likely to encounter. The idea was that if I can make their molars rattle, all the better.
I took a direct feed off the battery with fused 12 gauge multi-stranded copper, through a single dedicated relay triggered by a separate weatherproofed momentary-on toggle switch affixed under the OE horn switch, within easy ergo-friendly reach of my thumb.
I figure they've likely saved my butt from a dozen or more close calls that otherwise would've been much closer (or worse) since I installed 'em some 5 years back.
To let 'em sing at full throat fully unimpeded, they're mounted "semi-floating" on reed-thin stainless steel straps made from large "banker's clasps", available at any office supply, and stabilized by zip-tie up to the mounting struts in the Stucchi 1/4 fairing by short lengths of silicone automotive tubing (hidden inside the fairing). The horns aim forward and down for reflection off the road. Judging by the recognition they get in traffic, they get immeasurably greater respect than the OE squeakers, which I maintain for little "hya!" honks for the neighbors, etc.
I reckon that's "Hey, y'all!" in mid-Tennessee?