These guys in Perth build some great horns. I wish they were closer as they can't ship their larger horns. Hmm.. perhaps we could fill a large storage container and ship them to New Orleans :). The horns are in the following flare rates: 160Hz, 204Hz, 340Hz, 425Hz and 550Hz. Those of us outside of Australia are restricted to the 425Hz and 550Hz. They sound superb and would do well on top of any big bass horns. Check out the impressive curves here http://azurahorn.com/azurahorn_horns.html.
A few examples from their gallery. Their push pull horn is very interesting.
I like 'em.