I was just wondering if any one here know anthing about air steam horn ?. I mean its like this : It sounds like some one sprayin nos (but without nos).

I saw on the street the Mustang other day. I dont know what he got (either a blow off vaule or spray nos) but that thing making a big loud crazy whislte sound just like spraying the nos( but he was standin at the stop sign) or the sound of the boiling hot water comes out from the water steam.

Heheheh i know this is lame but i been searchin for this thing but i have no clue what is it. So any help masters ? lol Thanks again