Hi All,
Don't mean to clutter up the board or beat a dead horse with air horn issues but I'd like to collect as much info about as possible about air horns. Would anybody be able to answer any of the following about Grover emergency air horns models 1510 and 1512-

First, how can I determine which model horn I have, do I measure from the flare of the trumpet back to the bell? flare to the threads?

Second, Is there a way to change the pitch of the horn, make is sound lower or higher? Change in air pressure, changing the lengths of the threads "stanchion" (that's where the air is introduced right?)

There is a regulator where 3/8" the lines T off, where should that be set? The regulator can be set from 60psi to 130psi.

Thanks in advance.