We spent a weekend a while back installing a Clarion android auto head unit in my son's 97 JDM Legacy RS and a couple things came up that I didn't see easily accessible through searching this site figured I would put the information out there.

1. DO NOT USE ANY OF THE WIRES LABELED ILLUMINATION. This was a nightmare luckily I happened to wire mine in a way such that only the fuse blew and not the hard to find, hard to access, and kind of expensive illumination module... These cars have a module that controls all the dash illumination if you attempt to use these illumination wires on an American head unit you could set your harness on fire, blow a fuse, blow your illumination module up, all sorts of stuff. I guess the standard Japanese method is to measure a resistance while Americans apply voltage. Real bad news... Tape the wires up and never look at them again. I even have the factory wiring diagram and the same pins on the American harness say "illumination" on the Japanese harness but they are not compatible. Thank me later.

2. The factory power antenna is somehow two wires that go to one eyelet terminal with a screw that holds them on... I have never seen anything like it in all my years good luck finding an adapter. We just cut the wires taped them and tucked them away. My kid is never gonna do anything but stream anyway.

3. Aside from the illumination wires the American adapter harness worked fine.

4. Routing the wires (nicely) to the subwoofer under the carpet required removing basically the entire interior front seats, back seats, center console, etc... The carpet in the car is so perfectly and tightly conformed to the floor there was no routing the wires without removing stuff.

I've installed a lot of car stereos in my life (30-50 I would guess) this was the most difficult I have ever encountered.