I saw first hand today how much of a difference the size of your air tank makes. While mine is as large as I can fit under my Trailblazer SS…being 5 gallons…I checked out a friends K3’s on his F250 on Saturday. He has a 12 gallon tank mounted in his toolbox, with twin Vaairs doing the filling. He feeds the horns the same way I do, through a 1/2" SMC nickel plated valve. His are alot higher pitched…but the sound is instantaneous…and super loud. To me, his sounded like an Amtrak train…where as my P3’s sound more like a freight train. I was envious of how quickly and loudly his horns work, and he was more impressed with how much more of a natural and realistic sound my P3’s make.
Good to finally see someone remotely close to hear with a good sounding set of train horns…I believe I am the only one in the general area sporting a set. Not that this is a bad thing. 
Just wanted to share my experience…
