I had Hellas on my STI. I might get them again for the BRZ. The horns I had were Supertones and trumpets. The Supertones give off a shrill, high pitched tone. The trumpets gave off the nicer sound that I had grown accustomed to on cars like: Acura TSX, Honda Accord, various BMWs, various Mercedes-Benzes.
The hardest part of the install: making that wiring harness - 2 relays for 4 horns = my fingers were numb.