well, I got my horns for a surplus shop for cheap and it wasn’t working. turned out that the tuning screws at the back got loose so it no longer worked and so it got sold really cheap.
I tuned it for max output at 100psi with a pressure washer hose with 5/16" ID.
since I’ve been reading about more air flow = louder…When I upgrade to a bigger air line, do I have to retune the horns?
What kind of horn is it? Do you have a picture of it? I haven’t heard of any horns that need tuning other than an older Nathan horn such as an M or N series.
I think it’s some sort of semi horn. Brand is Kitahara.
it has those allen screws at the back cover that pushes to a disc that then pushes the back of the diaphragm. I think the shocker horns have those too.
my current horn is the white one. That’s the only pic I got that has it not installed under the car.
After gazing at some Asian model named Kitahara for a few minutes on google, i can’t find anything else about the brand, but, cool!, hey if it works! 
Shocker horns are pre-tuned. The screws in the backcaps just hold the backcap on.
uh, I meant that each horn, besides the screws that hold the back cap on, has another screw exactly in the middle of each back cap that is used to adjust the disc that pushes on the back of the diaphragm. I saw some pics of the shockers and they have those too.
I forgot where I read it, but somewhere in the hornblasters site, I read that it should not be readjusted because each is tuned by a specialist… so yes, shockers are tunable.
but since many use them from a wide range of air pressures, I may not bother to readjust mine when I upgrade the air lines. maybe when I get to replace the diaphragms with brass (couldn’t find stainless with the right thickness) then I’ll re-tune. the original ones are plastic but in very good shape and very clean when I got the horns.
BTW, I gave mine a long blast under a tunnel on the way home. I didn’t notice that I forgot to turn on the compressor. I’m guessing pressure dropped to about 60-80psi at that time since it took a bit while for the compressor to stop again when I turned it on. but the horn blasted about the same volume. I guess I tuned it right when I fixed it. 
anybody know what the allen head bolt on the main peice that holds all the horns together??i was thinkin maybe tuning??
Hm, the shockers I had didn’t have those screws in the middle of the back caps… Must have had the old school ones.
I found a couple of pics of the horn when I got it from the surplus shop. while it’s still dirty and not able to make noise. 
