Db numbers can be deceiving. I have the Stebel and would recommend it hands down. And I bought it mostly based on the 139 db (advertised as 140 some places). The tech specs on it say 139 at 6" from the bell, and it drops quite dramatically from there. I think most others would have a similar curve, and if all horns use a db rating at 6" then that's OK.
And yes, use the relay!
