Hi Charles,
  To the best of my knowledge ‘flexi silicon wire’ is basically a copper conductor, so provided it is correctly rated (sized) power loss will be minimum.
   ‘flexi’ means that the copper conductor has been made up of a large number of thin wires all together allowing it to bend easiley.
   ‘silicon’ is the silicon rubber insulation (cover) on the wire which, as well as being softer than most plastic insulation, is very heat resistant and does not melt.
   The working voltage of most wires will not be damaged by 6 or 12V (voltage rateing is the max voltage that can be safely applied to a wire without breakdown of the insulation)
  
  As far as current ratings ,  for your worst case example,
    I=W/V       I=100/6    say 20A max,
   from my previous post 2.5 sq.mm or 14 AWG wire will be OK.
  Power loss in the wireing can be estimated useing the resistivity of copper the length of wire used and its cross sectional area
      R=rho x L / A   this shows the thicker the wire the lower the resistance, the longer the wire the higher the resistance

Cross sectional area mm2    Resistance mΩ/m  
    1.0                                               18.0  
    1.5                                               12.0  
    2.5                                               7.4  
    4.0                                               4.6  
    6.0                                               3.0  
   10.0                                             1.83  
   16.0                                             1.15  

Using the previous figures 20A with say 2meter of wire
would give a volt drop along the wire of:
        v=I x R    v=20 x (7.4 x 2) mV
                   v=0.294V
So you would loose 0.294V for each 2 meters of wire in the circuit
Sorry to be long winded I try to give explanations not just statments

Hope this helps Tom

PS sorry Tim we seem to have hijacked your thread