There are actually two horns and they are both located behind the front cladding on the passenger side. I THINK there is one on either side of the foam "rib" behind the cladding. I actually moved them closer together when I located the ballast for my HID's right under the headlights behind the front cladding and the horn sounds awful now. The two notes are dissonant and they sound even worse when you get the two horns near each other.
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless