With the air tank I can prob hold 10 seconds on a blast then take 20 seconds or so to recover(air pressure and hearing). I don't really see any possible reason to hold it for 10 seconds though 3-5 sec is way more than enough. Usually I can get two short 1 second blasts before the compressor kicks on for a few seconds to refill the tank.
I don't think anyone would ever really need a bigger tank than that just to run a horn. It does good and the whole setup fits under the hood of my metro. If you want realistic sound run 100psi but for super deafening loud run 150psi
I do think it is funny when I get stopped at a train crossing and my horn is louder than the train's. The conductor usually looks at me like I am nuts for putting something like that in a metro
Accord? I dunno, maybe the new ones are better, but my 94 has a weak "meep meep" metric car sound. Now my 1967 Buick had a HORN on it. I tried to hook that baby up to my 360 Honda, and it killed it when I pushed the button, LOL!
If you want a 134 dB airhorn that would be easy to install, look for the Nautilus horn. It is built all in one piece and supposedly has a relatively short delay. It has the italian sports car air horn sound.
When I upgrade horns I go to the local pick your part junkyard and find an older cadillac with the dual horns that ground through the mounting bolt. They have a green wire coming out of them as opposed to the ones with a green and black wire. These horns are super loud and have a nice low air horn like tone. My horn causes crazy/retarted drivers to swerve back into their lane now. Try it...they are cheap($5 here in phoenix for both horns)