After the harness edit, it was time for install. Not only did the new harness (grabbed from the Pearly's old engine) now have only the required connectors, it also didn't have a vampire tap on its TPS connector.
(Screwdrivers point to removed connectors; new harness is at top.)

The harness was a little tricky to fish out from under the throttle body, especially with all the additional mechanics underneath it.
The Nismo injector connectors were different than the Subaru ones, so they needed to be swapped. A very tiny screwdriver's press on the plastic tabs next to the electrical hoozies got them out easily.

I was a little concerned about pulling off one of the connectors while replacing the harness, so I removed the airbox from the throttle body. This reminded me of why we never remove the airbox from the throttle bodies. It's a pain in the ass to get it back on.
No more vampire tap on the TPS (brown). Note that the idle controller normally found under the throttle body is actually relocated next to it (grey connector, tan actuator).
All told, the harness fit back into place pretty well. I probably made a mess of the hoses putting them back in, so I'm going to revisit their locations later. One additional change I made was fixing the canister purge solenoid to the intake manifold so it wasn't floating on top of the engine. It's kind of hard to see, but it's between the bypass runner and the intake, under a hose.

Always handy to have reference material.