I searched but just got confused, so maybe someone can answer this. I have the stock 2003 Nav and want to add an aux cable (stock head unit, not H/K). Is there a separate port for the aux or no? Thanks.

 

I have an '03 and Nav. I detailed what I had to go through to install it here, complete with pictures. The Nav occupies the space needed for the aux, but does not use the same terminals, It's a simple matter to move the wires from one connector to the other.

 

Thanks Greatbear. Success. I opted to do it without removing the head unit, which is a bit tight switching out the wires in the connectors. Near impossible actually, but somehow I did it. Now I'm just waiting for the DVD player.