I've got a voltmeter on the Strom that's just a series of LED lights. 3 yellows at the bottom of the scale (discharging), 4 greens in the middle (just right) and 3 reds up top (too much voltage). Every time I hit the horn or turn the PIAA's off I can see the meter light up all the way for about a half second...
The horn (a Stebel) and the piaa's are both on their own relays.. Nothing has gone pop yet, but it is a concern. Maybe your 1200's electrical system is more robust and better able to handle the pulse?
IIRC from my electronics schooling, you need an RC filter (a resistor and capacitor in series with each other) put across the coil (electromagnet, inductor, kinda the same thing in this case) to absorb and safely dissipate the pulse generated when the electromagnetic field collapses in the coil when you remove power from the relay (let go of the horn button). Too big a capacitor and resistor and it'll take too long for the horn to activate, too little and it'll be ineffective. Kinda like a shock absorber for the electrical system. I'll bet somebody makes one commercially but if not I'll only ask for 20% royalty
Keep us posted!