There's no loud horn you can safely just "plug in", you'll need
to add a relay... those air horns are good, and BigBF horns
under the swingarm are good. I have BigBF horns, I didn't
want to see the big air horn, even though most of them
are chrome...
-Mike
Absolutely should have relay.

A Wolo will mount in the stock position with a little fussing, but I prefer mine as shown.
