[shifty]

For reference - some pictures of what I'm saying from the install on my '03 GMC Sierra from last year or whatever.

Here is a picture of the rubber grommit around my power wire coming in from the engine compartment:

http://shifty.org/pics/truck/stereo_...l/IMG_0968.jpg

I used 00 gauge wire because I was powering a couple of large amplifiers that needed the juice. Here is a picture of my fuse that I installed about 20" from the battery:

http://shifty.org/pics/truck/stereo_...l/IMG_0967.jpg

I do not have the power wire hooked into this fuse block (the piece that goes from the battery to the fuse) because I didn't want power to reach the amplifier yet

Two things about running wires: First, run your power wire cleanly through your vehicle where it will not contact metal or short out. Also, never run your speaker wires anywhere near your power wires or you can introduce electrical noise and you'll hear feedback, "alternator wine" or other noise/distortion to your speakers. This is an example of how I ran my wire in the truck:

http://shifty.org/pics/truck/stereo_...l/IMG_0971.jpg

And:

http://shifty.org/pics/truck/stereo_...l/IMG_0975.jpg

Mount your amp(s) somewhere safe where they will:
1) Not get moisture.
2) Have plenty of room to breathe so the amp won't overheat or melt something.

Example: http://shifty.org/pics/truck/stereo_...l/IMG_0982.jpg

Be sure to ground your amp somewhere solid - don't just screw the ground wire to the body - preferrably, bolt the ground wiring with the correct loop/ring to something that attaches to frame. A good ground is essential to complement that solid power wire.