I do indeed
It started when I was nine years old, my brother was the manager of a Hi-fi store and after school he made me go to his shop and re-cone woofers for customers, those woofers from companies like B&W ATC, Tannoy and KEF sold kits to repair them and it was really easy, after 10 years i started to make and buy my own parts and make my own woofers, i did this so i could taylor the characteristics of sound, better know as the sonic signature.
Hi-fi and audio have been a part of my life for over twenty years now and i start a small company making woofers 2 years ago, i can make almost anything within reason, but am limited to the parts i can buy right now.
The 900 has a great body shell for sound but the front sound stage is rather low, so I designed an open di-pole ribbon planars for the sun visors which are at eye level, added to the bowl window gives a very deep and wide sound field with no real sweet spot.
People always ask me, "where are the speakers? i cant see them"
I point at the Ribbons and they says " What is that"
And i say never mind, as it takes to long to explain.
You only need 5 watts of class A amplification and you can have 103dB of sound (A weight) which is linear from 500Hz to 50,000Hz +- 3db
If your happy with your stock system and enjoy the music thats all the matters.