Paulkam

Ok, after searching days on end, up and down, highs and lows i found next to nothing with my searching.
i have an 03 LX with factory sat nav and i really wanted an aftermarket head unit.
I wanted the adjustability, bluetooth, mp3 etc.
If you remove the tape player however, the nav and your climate controls will no longer function.
Sorry i didnt take any pics along the way but i hope this can help someone out there.
Im now running an Alpine head unit, JL component speakers, 4 channel amp, alpine mono block amp and a 12" alpine type R sub.
Here's how i went about it:
Behind the tape player you have 3 plugs, if you disconnect the middle plug the nav/climate will no longer function. I believe this plug has 6 wires, I read somewhere that you could put in a resistor between two certain wires and you will have full function of the NAV. I went to the local autoparts store and brought several resistors of different values and tried many combinations of two wires, after hours and hours still no luck. So instead i cut the plug and extended the wires to the drivers side footwell. I then dismantled the tape player so the face of it was no longer attached to the actual metal casing. mounted the casing up in the footwell as there's a perfect spot to put it. soldered the plug to my new extensions and plugged just that middle plug back in.
Head unit was wired in and i ran 6 RCA cables to the rear.
i then removed the drivers seat and located the factory amp. Got myself a AA battery and started looking for the speaker wires. Now, under the seat there's two units, one is the amp, one is the gps. The amp has 8 wires on the plug that are slightly thicker than the rest. If you pair them up and put a AA battery on the wires you can locate which wires belong to which speaker, HOWEVER 6 of the wires will give you the passenger door speaker, and each of the rear speakers. If you put the battery on the remaining two wires, you'll get nothing on the drivers speaker at all. I believe those two wires are dark and light green wires. Now if you take the plug from the GPS, this should have 2 dark green, and 2 light green wires. For the drivers speaker the amp goes into the gps, and out to the door so that the voice guidance on the gps can be heard though that speaker. You can wire the amp directly to your speaker, or as most people would, i assume is keep the voice guidance and wire your new amp in before the gps.
Note: before all this you will want to set your gps voice volume to where you personally prefer it as the voice guidance volume will no longer change according to the stereo volume.

Please feel free to ask any questions, I hope this can help someone and skip all the stuff I went through to try make this work.