I've worked for a place importing Lowther horn drivers into Germany, in the early 80s. That was when their designer, a chap by the name of Donald Chave, was still alive.
If you put them into the recommended horn enclosures, you'll end up with some of the best loudspeakers money can buy.
One word of warning: be prepared to replace *all* of your audio components. These drivers have a very high efficiency, they are unforgivingly precise and even the slightest hiss from a low-end amplifier will sound as if you had compressed air leaking somewhere in the room.
When I started working for this place, I was more than a little confused when I watched the owner deal with customers who had obviously entered the shop ready to part with a few grand for a set of, say, Cabasse speakers and he let them get away with just two drivers and a blueprint for the cabinet.
I soon understood why. Within weeks, these people would be buying thousands worth of high-end gear. Amplifiers, turntables, you name it.
We had a demo system running for a time, consisting of two Lowther chassis on simple wood panels, hooked up to a Dynaco valve amp. Below, there were two bass cabinets, each with a 40 cm ACR chassis and two KEF passive units, driven by an SAE 2 x 400 w amp. Those were the days when Pink Floyd's "The Wall" had just been released. We had lots of fun with that. :-)
Ralf