The sleeving is thin and doesn't add a lot to a single wire....but it has that rough texture so when multiplied by 80+ wires coming out of the psu it definitely adds up. I have another 750 PC P&C psu that is identical except blue, before the build is done I'll take some comparative photos of the wire mass, stock vs mod. I'd say that it's almost doubled the wire girth coming out of the psu now.
Yeah, my two concerns for now are these wires fitting behind the mobo tray and then also fitting between the mobo. Considering I have the 24pin power supply, 5 PCI-e power supplies and an additional mobo molex power supply all coming from the same side of the board I'm a bit concerned that I won't be able to squeeze the mobo down low enough to get the screws in.