I would recommend new wire even if you are running the speakers off of a higher power HU.

I did not have much problem pulling 14g thru the doors on the cars I have done.

 

I am 6 foot 4" with big hands and let me tell you running the speaker wire was no fun at all. If you are smaller it will be easier. Just make sure you get the kY ready.

My hands were raw and bloody by the time I finished. Nevertheless it was worth it for the peace of mind.

 

Why?

 

Larger gauge wire = less impedance = less voltage drop across the wire and more to the speakers.

Efficiency

 

Please show me the formula for impediance/gauge of wire/voltage drop and apply it to the scenario.
I'm willing to bet that because of the power/distance numbers the difference will not be significant enough to make any difference.

 

Here is some basic info:

http://www.prosoundweb.com/install/sw/gauge.php
http://www.roger-russell.com/wire/wire.htm


Who really knows if it is 4 feet of wire or 40 feet - nobody can be certain how Honda routed that wire from the HU to the doors.

I prefer to error on the conservative side.

 

My speakers are ran with upgraded cable all the way to the door, where its tapped into the factory wiring, then on the inside of the door, it's reupgraded speaker wire to the crossovers, and on to the speakers. I can't imagine the 8" of factory cable being that big of a deal, although anyone here is welcome to come listen to my system to see if it sounds bad.