For a truck this size it has a pretty weak horn. I pounded on the horn at an intersection last week and no one even looked. I dicided it's time to upgrade to an air horn. Dual 160db horns powered by a small air compressor. I think that will get peoples attention! The compressor is useful for other things too such as cleaning or filling the tires back up if you air down to offroad.

 

Let me know what you end up with.
I would like to upgrade my horn too.

 

Check out www.jcwhitney.com they have a large selection of air horns. You can get a good one with a small compressor tank for $200. It will sound like a large semi truck. 135 PSI so it is useful for many applications.