Does the speaker wire harnesses that Crutchfield offers actually work? These are the harnesses right here http://www.crutchfield.com/cgi-bin/S...=1&cc=01&avf=Y I also want to know which is better to use these or just use the factory wires as a direct port. I have a wire diagram already so I know which wire comes from the amp and which comes from the HU. I also want to know if these HU wiring harnesses are helpful, http://www.crutchfield.com/cgi-bin/S...=1&cc=01&avf=Y Thanx

 

The HU wiring harness is a necessity if you want to install an aftermarket HU and don't want to hack up your stock wiring...it's a very worthwhile investment for $10...
As far as the speaker harnesses, I would think they're necessary for installing aftermarket speakers while using the stock wiring - but I've never done that. You could also cut the wires off the stock speakers and make your own wiring harness...