Ouch ouch ouch...

Oh well... AFAIK you could snip anything except the power wires (+12V, switched +12V and ground) and it'd still boot and work.

The mic input doesn't at this moment have any functionality at all; future possibilties that could happen are voice control, active sound silencing, auto equalizing setup...

Serial: Obviously you can't connect anything serial in the car - PDAs, GPS, video generator, ODBII diagnostics/control.

Personally, I'd go a long way in investigating the possibility to cut up the car instead.

/Michael