once the tab is bent out of the way, you can easily mount the horn to the body using the same screw that held the stock horn bracket in place. when that is all said and done, you must ground the ground wire you already attached to the horn. I used this screw circled in pink because it was close which meant less wire and less a mess:
to provide power to the first horn, simply slide the connector that powered the stock horn off the terminal, and slide it onto the positive terminal of the hella horn (the silver terminal)
congratulations, the first horn is done! Now onto the second.
SECOND HORN:
the second is a little more difficult to mount. I was going for the subaru look when mounting my horns, meaning the close together, symmetrical, centre grill look so i had to do some modifications to the bracket provided with the horn. If you unscrew the nut on the back side of the hella horns to release the bracket, you'll notice that the bracket is actually comprised of 3 skinny brackets pressed together. One is strong enough to hold the horn, and one is all you will need to mount the second horn.
the best prexisting bolt i could find to mount the second hella to required me to alter the bracket that came with the hella horns. I took two pliers, grabbed the bracket by either side with either set of pliers, heated the center of the bracket up with a torch, and twisted the bracket into the shape that was necessary to mount the horn. Heres what it looked like afterwards:
and this is where i mounted it (by simply unscrewing the existing bolt and bolting it down):
if you are not looking at the car in real life you might ask why the bend is necessary as from the picture it seems you could just bolt the bracket on straight, but the spot in which it is bolt on is actually angled towards the cabin of the car so the bend in the bracket is necessary to mount the horn so it is parallel with the grill and perpendicular to the ground.
once you do this and mount the second horn and bracket, ground the second horn's ground wire. I used this screw (again just because its close meaning a short piece of wire and cleaner install):
