Welcome from Droitwich Spa
I too struggled with the standard horn but couldn't find a suitable place with enough room for a bigger horn. So as not to block air-flow through the radiator & fan shroud on the RH side of the engine, I added a 104dB horn turned 90°, and then refitted the stock horn below it AS WELL. The twin tone horns are now plenty loud enough, and was a cheap fix
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IT doesn't look like in this picture, but there's plenty of room between them and the brake lever, so no interference with your boot !