What are you using for replacement horns for you FJ's? I've tried https://amzn.to/38bQbZe and it didn't last more than a couple of months. I'd like something loud with out adding a full blown compressor unit and train horn.
The horns used on the current and older Tacomas sound great and are loud and are currently available from Toyota.
Go to a Toyota dealership and ask one of the salesmen to show you a Tacoma- then honk it's horn and take a look at it when you pop open the hood.
They require a relay when wiring them up as most modern horns do. No biggie.
I added a relay and a set of 4 note Cadillac horns from a junkyard (early 90s Caddy). It now sounds like a tugboat and has a commanding tone that has actually stopped traffic (when required). If you want a brighter sounds, there are 3 note sets of Buick horns (same era) that also speak loudly. These horns might be GM's most useful contribution to the automotive world.