This topic had me thoroughly confused for several messages until I realised that in America you are using the name air horn for something completely different than my knowledge.
In the UK an air horn is typically a device with a compressor and horn(s) intended to make a loud noise when you press the button at the centre of the steering wheel.
Whereas the tubes that feed air into a carburettor (which is what you are talking about) are usually called air trumpets in the UK
The Lotus parts list calls them trumpets.
http://www.lotuselan.net/wiki/EG_-_Engi ... arburetter~~~~
I'm not complaining, just noting yet another difference between American English and UK English language.