check it out!
http://www.trainhornforums.com/album.php?albumid=124&pictureid=859
looks cool but why use 4 valves? Does it equalize the pressure better?
well, i have 2 horns. a K5LA and a P3. I wanted to be able to select which horn to blow with my graham white valve so i installed a solenoid valve after the graham white valve in order to select which horn to blow. I can also blow both at the same time if both valves are energized.
The other 2 valves are connected to my horn button. You see, i have found that using the graham white valve to blow both horns at the same time, it is not as loud because i am Y’ing the 1/2" air line after the graham and i just seems to devide the air flow in half.
But if i use the horn button, i have a dedicated 1/2" line direct from the tank to the horn and it is just WAY louder. I have a panel of switches to select whice horn the horn button will control. Either the stock toyota horn, the P3, the K5LA and i also have an ambulance horn. any combination is possible. My installation is still in the works, i will put up some pics upon completion.
Look forward to your update , my g/f works at Graham White in Salem Va. Trying to talk her boss into a tour of the company.
Maybe she can get some free samples for ya 
I will have some youtube videos up soon explaining my entire installation in detail.
Hope for some samples for sure.Met let us no when those vids are up.