I started the teardown of the '87 FLHTC in prep for frame repairs . . . and found this. I'm not well versed in Harley's, but it seems to me that under the seat isn't the better place to install a car horn.

 

Somebody did that afterwards . Normally its under whats called a cow bell on left side.

 

That's different for sure.
The horns back then did need some help. Least they are a bit better nowadays sorta .
If it works it works lol

WP

 

if it's as loud as modern horns, it's fine there. I relocated my 2016 SGS horn to that area and it was still very loud

 

I got a seat horn……right after the double bean burrito🤣

 

My Dyna has the horn mounted on the frame right behind the rear exhaust pipe. It seems an odd spot, but it works just fine, and it does clean up the left side of the bike.

 

I mounted my air horn there years ago. Works great.😊