This thread describes the nav system in an Australian Liberty (very similar to USDM, except the nav unit sits behind the glovebox, and their OEM HU is a McIntosh, but otherwise the connections are very similar):
Subaru Factory Sat Nav Tutorial
I posted a reply there talking about the 10-pin power harness. I think that's a better way to go on those (finding the one for the aftermarket Kenwood nav units). Keep an eye out for that on eBay. Or look for a wrecked Legacy/Outback that had the nav system.
I might have the 20-pin plug and terminals for that. I could possibly make a harness that connects from there to the OEM HU's i88 socket (and passes through your existing factory wires for the HVAC, similar to my adapter for installing the JDM HVAC dash kit).
I don't think I have the 16-pin. Need to figure out what manufacturer and part number that is.
E-mail is the best way to contact me (see my home page). I've been very busy lately, so it can be a few days before I can reply.