not worth running new cables if using 6x9's, as the headunit is not too powerful for the standard cables, and if she decided to amp them in the future, surely it makes sense to mount the amp in the boot, with the speakers, so then just fit new cable there?

Yeh I no but she doesnt have enough cash to get a sub and amp combination and needed boot space so just running a set of 6x9s with components running off the headunit. From the other thread i presume its the green and green/black + violet and violet/white for the rear speakers. Would it be best to just replace this wire with better speaker wire at the plug incase she decided to amp them in the future? Also where is the best place to run the wires, under the carpet down the passenger side?

fitting 6x9s isnt a good idea, but anyway... the wires are there at the back of the headunit. the colours are in one of the last few threads in this section

Im fitting some 6x9's into a corsa that didnt have any rear speakers, therefore no speaker wire. Whats the easiest way to run speaker wire from the back of the headhunit to the parcil shelf? Thanks