I knew nothing about these installs and I just finished my entire replacement of my system, door speakers, rear speakers, amps, subs, head unit, the whole bit. I'd say right around 10 hours labor all together. Saved me $350.00.
If you wanna attempt it I can give you pretty good advice. My install was on an 04 GT. I'll put up pics of my ride soon once I get the rest of my goodies done on it.