Not sure if VW is going to introduce a OEM Replacement for its original Bicycle Horn? For a Vehicle its size, its simply ridiculous and unsafe. Sounds like they probably used a Single Horn instead of a Dual Low and High Pitch Horn.
Since its a VW product, I do not see why you cannot use a horn combo from an Audi or VW vehicle. If the original horn is a single unit, you might need to change the relay and fuse rating to allow for dual units.
I'm really surprised that the NHTSA hasn't set some minimum standards for Vehicle Horns. A certain minimum level of Decibels should be required as a safety function other then lowering your window and screaming!
I found a video of the Hella Supertone horns being installed in a Subaru (apparently that's what all Subie drivers do...). They sounded like crap. A pair of standard GTI or A3 horns sound much better.
The (single) horn is actually right behind the grill, to the left of the VW emblem (left side of the car). Looks like there might be a little extra room in there to squeeze in 2. I'm thinking the grill probably comes out the same way as a MK7.5 GTI, i.e. annoying, so I haven't tried yet. I also want to see if something can be done to avoid any modifications to the wiring harness/plug. I should have some time over the holidays to dig into it a bit more.