I ended up making up a stainless rail that bolts to the standard horn mountand goes across the frame, and another bolt thru the other side to sit on one of the bolts that holds the frame together as a locator, and stuck the horns on either end of it. It puts them on either side of the tank, just in front of and below it, and just above the downward curve in the header pipes. Not as pretty a mounting as I wantedbut it works and made for easy wiring, as I put the relay on the back of the rail and hooked the standard horn wiring to it, with a new wireto the battery for power. The horns're earthed through their mounting bolts which I was nervous about, but it seems to work so I'm leaving well-enough alone. I'll have to put a pic up I guess.
Matt
