(In order of importance)
- GPS-interface
- Keyboard interface
- Serial Out to a "dumb" display
- Cabriolet up/down detector
- CD-changer in
- CD-changer out
- Mobile phone serial port interface (or even Bluetooth interface! ((Yes, I have a bluetooth enabled phone))
- HAM radio TNC-interface, APRS?
- An interface that will produce a "beep" on the empeg-audio
- Ambient noice detector with volume or equalizer change

I'd pay at least 100$ for all this functionality :-)
I'd prefer a kit with all parts, but I could do the soldiering myself.

Marius (Escort Cab + Mark II)