I have installed them and they work great. Wow, what a difference..
I took off the stock horn and placed the relay and wirings in it's place behind the chrome horn cover.
The only doubt I have is that I have taken the current from the stock horn's + cable, and placed a fuse holder there in series. But I am not sure about if this cable is already fused or not, and what will fail if the new horns blow it's fuse if any (not the new one I have installed near the relay).
Just a note, I've used the crash bars to hold the horns, one at each side, and I like it this way.