I own a 2006 Mustang GT so I am going to warn you of a couple of caveats.
1. Infinity speakers ****! I had a set of four 6x8s (682.7cf) in mine and while they were a slight improvement over stock, they had HARSH highs that were only worse upon adding amplification.
2. The Shaker 500 Door "subwoofers" are phased weird and could cause cancellation with your trunk mounted subwoofer should you try to use them together.
3. The trunk sucks and has an odd opening as well as some odd dimensions. I know of some who built their enclosure in the trunk!
Other than that, the car is fairly easy to work on. PM me your email address and I will send you the instructions on how to disassemble everything.
ETA: Here is an easy way to run a power wire into your Mustang:
1. Remove the fender lining on the passenger side.
2. Locate the wiring harness where the antenna runs in (see orange wire)
3. Cut the rubber nipple off and run your wire on through. You will easily be able to see it on the other side of the firewall:
I was able to squeeze a 1/0 wire through mine with no problems! I forgot where I stole the photos from, but I have to thank that guy for the inspiration. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif