as promissed a while back..... here are the layout schematics for power, audio, and buttons. Please double check the schematics, it worked for me but it might not for you. Double check everything before you hook it up to the car (it is not going to be my fault if you brake something).
Here it goes:
and last the Button Layout
The next step is going to eliminate the Tone Control K100, the Carnetix Power Supply + Pololu PwS, and the ISL22511. Even though it was a good idea to use them at the begining (was a lot easier to get started) but now they are obsolete. The audio control is done via software in android 4.0 (don't need ISL22511 and K100 any more) and the Carnetix is just an overkill for the job. I am working on implementing the power circuitry from this SourceForge project. It has a battery option that would also put less stress on the car battery while the car is off and it would allow a setup with "instant on".