My horns sounded anemic, too. Replaced them with OEM and they sounded better...but still pathetic (mine were up front, and they're easiest to reach from underneath, by the way).
Even though my horns are now brand new, does anyone know where I can find a really LOUD horn to replace them with? I wouldn't mind them sounding like a train, if it got attention when I needed it!
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I also just bought the metal retainer (don't know what else to call it) just under the steering wheel cap, that has the plastic grommets on it that activate the horn. The original was missing a couple of them, and the horn would only sound if you hit the lower left side of the button (which is hard to do in a pinch, particularly making a turn, when the "lower left" has moved! :eyerole
Going to try to put it in this weekend, when I have the battery disconnected to install a starter heat shield anyway!