My Volti upgrade on my 1974 Brazilian Rosewood behemoths (KB-RO) transferred them to another level sonically.
I went for the full upgrade (highly recommended)! One of the most noticeable / instant improvements was the imaging of the speakers. With the original Klipsch components, there really wasn't much imaging at all, basically two point sources in the corners...
With the full Volti upgrade, the loudspeakers disappeared with a nice central image in the middle, pretty mind-blowing!

Kudos to Greg on improving an iconic design!

Cheers,
Pete