As usual a great DIY!!
Have you tested out the USAspec Aux in? If/when you do, test it with a device that is also charging while playing (to see if there is any noise/ground issue).
Also, you mentioned being able to save off of the CD changer. I'm pretty sure the cd changer does not have the expansion port to connect a slave cable like the Sirius does. So you can use a Sirius + CD changer, Sirius+ipod, but not cd changer + ipod (without splicing, hacking etc).
Great pics too!