Since I was replacing a single horn with a dual, I had to do more than that. I removed the bolt that mounts the factory horn to the brace. I used that bolt to mount both of the horns to the brace (one rightside-up, the other upside-down) with a nut on the other side. I made a splitter adapter (since I didn't want to splice) using a butt and 3 slot connectors (1 female for the power side, 2 male going to the horns). I used 1 ring connector for each horn for the ground (the factory horn grounds through the bolt -- no ground wire). I pancaked both rings and put the mounting bolt through them, then through the brace, then tightened up to the frame. The relay that came with the hella horns appeared to be the same as that factory relay, so I didn't use it.
The female slot connector had a harder shell and the factory power slot connector wouldn't fit in it (it's rectangular), so I had to shave the corners off. A softer shell probably would have fit around it without any issues.
