Comparing the Vespa GTS stock horn to a copycat Stebel Nautilus dual tone air horn.
The stock horn is a small electric disc horn which makes around 96dB of annoying noise, whereas this airhorn blasts out around 139dB of get-out-of-my-way.
This is not a copy of the Nautilus Compact model (which I found out while trying to install it!), but the full size version.
It is an EXTREMELY tight fit and required the re-routing of coolant pipes and wires to get it in place so I really do recommend going for the official Compact model from Stebel.
For full sized motorcycles as well as the Vespa LX (which has more room behind the front panel than a GT/GTS) this copy will probably fit perfectly.
You can buy the Stebel as well as fake-o's from eBay and Amazon.
Additional things you will need to purchase with the horn include a good amount of 20+ Amp automotive wire, 20 Amp inline fuse, 20 Amp ring connector for the battery, 2x 20 amp butt connectors and a load of 20 Amp spade connectors.
Tutorials are at:
http://modernvespa.com/forum/wiki-gt-stebel
http://scootercommunity.com.au/forums/p/10415/67423.aspx#67423
http://scootercommunity.com.au/forums/p/11027/110449.aspx
http://scootcommute.blogspot.co.uk/2013/05/project-report-installing-stebel.html?showComment=1370125025729&m=1
P.S. I'll try not to use my new horn for the sake of it ;)
