While there is no "Patch 1.0.4" from the original developer (Black Rock Studio), the community often refers to the 60 FPS & Physics Fix (by ducon2016) as the essential "patch" for the PC version of Split/Second
There is no official or widely recognized (version 1.0.4) released by the original developers for the PC version of Split/Second: Velocity
Yes. These community patches have been vetted by the PC racing community for over a decade. They do not contain malware and do not trigger VAC bans, as Split/Second does not use Valve’s Anti-Cheat system.