So I ordered the 'sport horn' from Japanparts.com since I hate the stock Nissan horn. It was a gamble given I had no idea what the sport horn sounds like and it was about $90 shipped from Japan. It arrived today and let me tell you. It was worth the gamble.
It sounds incredible...very european sportscar-esque. You do have to pull off the front fascia which was somewhat painful but in the end it was well worth it. Don't hesitate to order these and install them.
Sound clip to follow.
***As an optional alternate install, the horns come in pairs...hi and low. The complete sports horn upgrade is rather high pitched (and I prefer it). However, if you only swap the 'low' horns and leave the stock 'hi' horn, you get a deeper but still 'sport' horn sound***
Link to the horns:
japanparts.com : PARTS DATABASE
Horn clip attached now. Didn't know a better way than a zip file...let me know if there is a way to post it directly.