Almost all cars have two horns as TheDude said. If you only have one horn, regardless of low pitch or high pitch, it will sound like a clown horn. It's hard to believe that the Supra would have only one (clown) horn.You'd probably be looking at 2 parts to change out. Hell, look at any other Toyota model horn parts. I'm sure it'd be super easy to switch out. Usually a low pitch and High pitch horn at least from my manufacturing experience.
Can't be worse than the STI horn lol. People upgrade theirs all the time.there have been several reviewers that have commented that it is the worst horn they have ever heard. I will say that I laughed when I heard it the first time lol