Dmytro here, based in Valencia, California. I'm not on a WR250 myself (yet), but I spend a lot of time around dirt bikes and trail riding, and this board keeps coming up when I search for honest WR250R/X advice, so I figured I'd introduce myself properly.
My day job is with Horn Guns (https://hornguns.com/) - we make portable, cordless train-style air horns. The trail connection: a weak stock horn is pretty useless on dual-sport rides when you need a hiker, horse rider or a distracted driver on a fire road to actually hear you. A loud handheld horn in the pack has saved me a couple of close calls, and it doubles as an emergency signal if someone gets separated from the group.
Happy to share what I know about horn loudness (dB ratings, what's road-legal, wiring an upgraded horn on a 12V system) if anyone's thinking about it. Mostly here to learn though - looking forward to reading your build threads.