Horns
First, in your manual, there is a procedure to enable/disable the horn honk on locking with the keyfob. I routinely have it enabled at home so I can do a quick check when I go to bed, but when we are traveling, like in an RV park, I don't have it enabled. . Too disturbing to close neighbors.
My air horns are so loud, as are many, that I didn't try to put them under the hood. They are on the vertical 'brace' that is at the very forward edge of the bed (about 6" behind the rear of the cab. It is a sheet metal brace that keeps the leading lower edge of the box from flexing. I have them aimed at about a 45° angle down so they hit the pavement. They are so loud that where they are on the truck isn't really important. . I also didn't tie them in to the stock horns such that as they are so loud, I won't be using them as a replacement for the stock horns, but as a toy instead. In the rare instance that I honk my horn at someone, they are usually either agressive enough or just screwed up and in an embarassing situation that I see no point in aggravating them further... . My air horns are ONLY for fun. .