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@dlearl476 posted:You need to install both. Separately, they sound like kiddy kar horns. It's the dissonance between to two frequencies that create the "attention grabbing" effect.
FWIW, I installed my Hella horns without a relay and they are plenty loud.
Same here. I also plugged in Hella horns where the old single horn had been (without a relay) and no worries.
Night and day difference in sound volume (and quality).
These are the ones I used.
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