I just installed some Audi 5000 horns on my 85' Westy.  They are twin tone
and required a little rewiring at the horn area

along with a relay. The stock horn has an internal relay. That is the reason
why you must use a relay to make these

Audi horns work.  The horns were 6 bucks and the relay was free ( your basic
Bosch relay)

It's nice to have that loud Euro sedan horn on the van, it really sounds
like the van should.

Malibu Tony 85' Westy