Finally got around to making my harness and getting it all installed.
All I can say is, WOW. What a huge improvement.
I was pretty much resigned to replacing my head unit with something aftermarket but now I might not be so hasty.
Huge thanks to everyone who got this figured out and posted for the community, and to FR-S2GT86 for putting together such a comprehensive step by step guide. I'm just blown away by the sound quality for being such a simple change.
