PIAA 85112 500Hz + 600Hz sport horn, AND Wolo Bad Boy
on NA6 Miata (which is just as invisible to other road users as motorcycles)
Same PIAA horns on S4R
which has a pair of big, umber colored conspicuity lights.
Still, loud horns are "must-have"...
All of them running on custom heavy duty wiring and
relay.