Postby Skrallex » Sun Jan 06, 2019 12:02 am
I think there's merit in both methods; installing the relay and harness means you definitely aren't going to overload the wires, and you don't need to touch the stock harness. On the other hand, the factory wiring can clearly handle your typical horn, including Hella horns, as Shaun has mentioned. Not sure about air horns, but I doubt they would be pulling 20 Amps, thats really quite a lot. Benefit of just using the stock wiring means you don't have to have extra after-market installed wiring coming off your battery, which is ALWAYS a plus in my books.
If you install the relay and harness, just make sure you install the fuse the properly. While a relay alone provides SOME protection, it's not an adequate short-circuit protection device. You should always have a fuse as close as possible to the battery positive to protect the cables and devices down-stream.