Again, the Bitfenix are extension cables which REQUIRES the original cables of the PSU for it to work. You aren't going to replaced it.
If you want to have everything sleeve from the PSU to your components, have a look at the AX760 and get the sleeved kit for it. http://www.corsair.com/en/power-supply-units/psu-accessories-1/professional-individually-sleeved-dc-cable-kit-type-3-generation-2-white.html
There is a site that does custom individual sleeving that are made for a specific PSU. I recall seeing a few kit for the Silverstone Strider Gold / Gold Evolution. If you can find it and can buy from there, that may be an option as well.