Injector threads
 

Going through my first annual with an FI engine. I removed and cleaned injectors with an unltrasonic cleaner. Should there be anything applied to the pipe threads to aid in sealing? Fuel lube perhaps?

A little pipe thread sealant is what I use.

Fuel Lube and typical pipe sealant will not survive the heat.
Anti-seize will work. No sealant required.