I bought all from https://www.gosumodz.com/ the crimping tool is the most expensive part but its woth it.
MDPC-X is also a good resource for custom cable sleeving
I guess u can get pretty much the same from Cable mod,
i actually build all the cables myself staying flexible as possible in case of hardware change, upgrades etc
No its all stock. I'm pretty happy as it is right now, under windows its dead silent and while gaming the psu gets noisy but bearable i would say.
Since the psu is clearly the loudest part i ordered another Noctua NF-A9x14 replacing the corsair one.