I have the 118db hella supertones on my WRX, because I was tired of people not seeing me and coming over into my lane. These horns are absolutely amazing and have to say that they have saved me multiple times. The reaction of the other drivers after a blast of these is almost funny. More than anything it keeps me safe.
I upgraded mine to Hella Supertone Horns from Susquehanna MotorSports in 2003. The price for both horns was $43.53. They installed directly in the factory location with the factory brackets. I solder up a jumper for between the ground terminal and the bracket (since they are not chassis grounded).
So if you need to pass anybody uphill they will give you the punch you need and is way cheaper than a turbo or supercharger
It should be listed on the best mod under $100
It reminds me my old 1974 FJ-40 , on which I installed a Mack truck air horn on top of the hood, just for the pleasure !!!!!! You don´t have any idea how fun it was, now as we grew old we realize how dumb or crazy we were on our teens