I just installed a Soundbomb mini horn on my fj-09 and was blown away by how much louder it is than stock. Installation was plug and play and fit on the stco horn bracket without any modifications. Price is good as well
 
 
https://www.revzilla.com/motorcycle/denali-soundbomb-mini-horn

Great - just ordered one.  Just what I needed.
 
Plus maybe a Stebel horn for the car.
 
You SUV drivers all drive down the middle of the road - I need a killer horn.
 

I just installed a Soundbomb mini horn on my fj-09 and was blown away by how much louder it is than stock. Installation was plug and play and fit on the stco horn bracket without any modifications. Price is good as well 
 
https://www.revzilla.com/motorcycle/denali-soundbomb-mini-horn

[ I did the same and car drivers now respond. Not all but far more than with scooter horn it came with.

I just installed a Soundbomb mini horn on my fj-09 and was blown away by how much louder it is than stock. Installation was plug and play and fit on the stco horn bracket without any modifications. Price is good as well 
 
https://www.revzilla.com/motorcycle/denali-soundbomb-mini-horn

[ I did the same and car drivers now respond. Not all but far more than with scooter horn it came with.

This is what I have used. It can cause whiplash among the unattentive. https://www.revzilla.com/motorcycle/denali-soundbomb-split-dual-tone-air-horn 

Interesting. Looks identical to the old Fiamm "mini-blaster horns which are $10 less than the Denali on Amazon Prime https://www.amazon.com/FIAMM-72112-Freeway-Blaster-Note/dp/B000DINKPQ. Speaking of Fiamm horns, one of the first mods I made was installing a Fiamm low-tone disc horns (https://www.amazon.com/FIAMM-72112-Freeway-Blaster-Note/dp/B000DINKPQ) which is a lot smaller and I kept the higher tone OEM horn for even more sound volume I recall paying about $11 at Advance Auto or PepBoys.  Note I have the added horn pointing forward rather than tipped down like the OEM horn...