Does kinking the wire of a psu affect power ouput?
No.  Electricity isn't like water, it doesn't mind going round corners (at least not on that scale), and a piece of copper cable can't collapse and close off the way a hosepipe can.

Kinking a cable still isn't a great idea though.  Bends over sharp edges, or repeatedly bending and straightening a cable can damage the insulation.  Then you can get an electric shock, or it can start a fire.