I've posted the thread on the E53 board, but since I'm here more than anywhere else on this site I want your input. The link to the original thread is
HERE.
Here's a vid clip of the horn too 
So basically I want to mount this bad boy somewhere inconspicuous and the only thing I can think of is placing a small winshield wiper fluid tank on the other side of the engine bay and trying to squeeze all the equipment to the left of the motor (on an '01 3.0i).
Anyone else have ideas?