Those look like the AM80 model. If they are, they draw 5 amps each, so you will need to replace your horn fuse with at least a 10 amp one (IIRC, stock is 7.5 a).
I have the Stobel Nautilus horn and have not heard any other aftermarket horn on an Elise and would like to hear yours some time. Our youngest son is going to be a freshman at the University of San Diego this fall, so I expect to be in your area occassionally. Maybe we can get together some time and toot our horns.
