I have them and use both horns. You use the relay they give you but you also use the stock horn wiring as well. They come with directions I believe but there is a how to on another website I used. Both are helpful but its pretty straight forward with the directions they give. You are basically running a few grounds, a wire to the stock horn, a wire to the battery and a few wires to the horns. The hardest part will be if you have the stock grille your going to need to shave some of it off in order to get the horns to fit. That is, of course, if you are planning on putting them behind the grille.