Adding a horn to my KX

I am sick of not being heard by the four-stroke crowd on the trails, it makes passing dangerous. I was thinking that if I use a 6-volt regulator, ¼ farad capacitor and a 6-volt horn it might work. Going to a 6-volt system should allow me to double the available amperage. Will a 6-volt horn require twice the amperage to operate and negate my whole plan? If not, maybe a small sealed lead acid battery with a regulator and a diode just for the horn in a 12-volt system? How much extra current do I have with a stock KX250 or KX500 stator? I don’t want to fork out the cash for a heavy-duty lighting coil if I do not have to, but I also don’t want to burn out my electrical system.