from my own experience i didnt have to run any wires thru the door...if im not wrong then there would be 8 wires for speakers behind the HU...what i did was to take the 2 front left + speaker wires and connected them and the 2 front left - and connected them...same for the right... now that they are connected i went to the trunk and disconnected the back speakers...then i hooked it to the amp...now i hooked the 2 back speakers with new wires and it goes to the amp...

oh yeah u got to disconnect the stock amp that is in the trunk...then u would have to extend the wires so it can be longer for it to be able to reach the amp...

again

1. connect left front and left back poss to poss neg to neg
2. same procedure as left for the right side.
3. the back speaker wires are now your fronts. u got to u new connection for the back.
4. dont forget to remove ur stock amp and extend the speakers so that it can reach the amp
5. connect it all to the amp
6. ur done.