Finished the C4 stereo install
The goals were to have a head unit that fits in the big hole and sounds good. I picked up the Pioneer FH-P4200MP.
I used the advise tips in the stickies and fashioned the front speaker housings to hold a pair of pioneer 4" two-way speakers. In the back, I managed to get a set of the base stereo system speaker mounts which hold a 6 x 9 speaker. These holes have the pioneer 6x9 3 ways. All the speakers were picked up at Walmart for cheap.
The plan is to use the head unit as a high pass amp for all four speakers and run a powered sub for the low frequencies. The pioneer is nice that way since it has internal electronic crossovers.

Last but not least - the iPod connection. Using the AUX adapter for the head unit - it gets you to a couple RCAs.

I then use a 1/8" female jack from radioshack,
cut up a pair of RCA cables and solder the ground and signal wire to the jack. Drill a small hole in the dash and glue the jack into the dash from the back side, plug the RCAs into the AUX adapter and then have a 1/8" to 1/8" male to male cable connecting the headphone connector on the iPod into the jack that is now on the dash.
After messing with the crossover frequencies and equalizer, it sounds great.
The biggest challenge was the wiring from the stock bose to the Pioneer head unit. It turns out that the tuner has all the connections and it's located underneath the glove box on the passenger side. A real pain to get to. And because of the distance, the harness wasn't long enough so I had to extend the whole thing. (PITA). Overall I'm very pleased. It looks good, not obvious, the sub doesn't take up much room relative to the volume, and it was relativly cheap. I think I'm into this for about $650-$700. Between Walmart and Ikesound, the component costs were bearable.
I need to take a few pictures of the finished installation.










