Subwoofer External Amp / Power Rating

[CM]

I have two questions:

1) Does the Subwoofer have an external amplifier or does it get all it's juice from the head unit? If any of you have looked at the back of the head unit, are the subwoofer leads thicker gauge than the others?

2) Is the "160 watts" RMS power or peak power? I contacted Honda and the tech said he thought it was peak power but was not sure, if so does anyone know the RMS rating? I am assuming it is 25WX4 + 60WX1. If anyone has a schematic that would be useful too.

I am installing a computer in the dash (navigation, mp3, fm radio, xm radio, and dvd) and don't really have any use for the factory head unit. I will probably replace it with a 5 channel amplifier running off of my soundcard. I'm also considering purchasing a single din factory reciever (from NAVI models) and installing it below the touchscreen.

Thanks.