There are two different tones of Honda (and most other) horns, high and low. The most common combination is one high, and one low. The NSX is unique in that it had a third. I forget if it's a high or low. I changed mine out with OEM BMW horns, which, coincidentally are Fiamm horns (Electric, as opposed to air horns shown above). I replaced high tone with high tone and low tone with low tone. However, on the NSX, the tone that has the two horns kind of overpowers the single of the other tone when replaced with the BMW Horns. I was able to get the BMW (Fiamm) horns to fit in all three stock locations, although it did take some creative placement angle to get the underhood one to fit, since the Fiamm is much larger than the stock horn.
In the case of smaller cars like the GS-R, they made do with only one horn, so what you're hearing is just a single tone. All you need to do to get the NSX sound is to get the missing tone, splice the wire, and attach the 2nd horn.
Honda/Acura horns of the '90s vintage were relatively weak sounding in my opinion, which is why I changed mine. The current ones have changed to a more stronger, Euro sounding horn, and are fine left as stock.
-Ben
[This message has been edited by Ben (edited 16 January 2003).]
