I just wrapped mine up not that long ago. My suggestions:
-TAKE YOUR TIME. This is not for the faint of heart.
-Have a plan for where you want to mount the fuseblock and pcm FIRST. i.e.- plan your harness routing ahead of time. I mounted my fuse block where the battery was. Had to open some holes up under it to get the harnesses through w/ their huge connectors.
-You do not need to unwrap all of the harnesses. Some you can leave alone, as you can (depending on where you mount stuff) end up w/ more factory harness than you need. Others you can get away w/ only unwrapping a portion of the harness.
-Unwrap/extend only one harness at a time.
-Extend only one wire at a time. This helps eliminate the possibility of screwing up. Knowing where your harness's destination is will help you know how much wire to add.
-Buy lots of electrical tape, shrink tube (
w/ the adhesive inside), solder, and/or butt connectors. NOT the cheesy red or blue ones you get at the auto parts store. I recommend the nice non-shielded connectors that you shrink tube w/ adhesive lined tube, for a good seal. Like these:
-DO NOT SKIMP on your electrical supplies. There is NOTHING worse than chasing electrical gremlins, and the few pennies you'll save on cheap butt connectors, electrical tape, etc. just isn't worth it.
-You will need 20awg, 18awg, up to I believe 14awg, if memory serves me right.
-Get good wire strippers. This style is popular, but the clamps that hold the wire in place actually break the wire jacket, so I DON'T recommend using them:
I LOVE the ones below. I have wired at least 5-6 complete FULL hot rods (front to back) with these. They DO NOT cut the wire jacket when stripping. Worth every penny, I promise.
http://www.matcotools.com/catalog/product/WCS191/WIRE-STRIPPER-RECESSED-AREAS/
-Last but not least- be
OVER protective of your wiring. I can't tell you how many times I've seen wires running unprotected along sharp edges of metal. When you unwrap a harness, save the plastic loom. A lot of it you can reuse to help protect the wires. If you're passing a wire through metal, be sure you put a grommet or some sort of edge protection on it. Consider every chafe point or edge to be something that can cause a short or
FIRE, and protect against it. If you're not sure, protect it anyway. Why risk it?