If you haven't already, you might consider a louder horn. Several have tried the Stebel Nautilus (myself included), I believe it's rated at 140db.
After several sets of pipes, I went back to stock long ago. Even with those I wear ear plugs every ride (having tinnitus since my infantry days is not fun).
I won't say I troll blind spots just to use it, but when I do get a chance, I press the button much longer than necessary, just so everyone will look around (especially at the offender). Although there were times when even the Stebel didn't do anything (old guy who didn't care, lady on a cell phone who still moved into my space, etc). Pipes wouldn't have mattered. And I've gotten to like the sound of stockers with 40k miles. They age well with miles. And the horn is only loud when you want it to be.
