I have 3 of them, customized for me by Uli Kuehnel, Boris's racquet technician for all of his career. I also pestered him for all the possible details as I was getting tired of reading oppinions here .. here is one of them being strung by Uli on is famous machine (it is a 60 euro string job IPDX style)
Perfectly matched at 347g strung
33.1 mm balance point
Extended to 69cm
Strung with a multifilament produced by Toalson for IPDXperience
2 ProsPro tacky overgrips (closest to what Boris used wich was a tacky overgrip roduced by Toalson Japan for IPDS), one no overlap one overlap directly the pallets
slightly shaved or polished edges on the handle for a more round and comfortable grip
Strung at 40 dynamic tension units (too much to explain here but each string is prestreched and tensioned according to the machine algorithm for this particular frame proportionally to it's length directoon and many other variables
It is a fascinating science to say the least
They do play great
As a side note, they feelmuch stiffer than what is supposed to feel