There isn't a lot of information on google for this change but its mentioned here...
2018 Nissan 370Z Coupe Press Kit - Nissan Online Newsroom
.."Without changing the engine's internal structure or components, engine performance is improved through careful refinement of Accelerator Pedal Opening (APO) and Throttle Valve Opening (TVO) angles"
Does anyone know if this feature can be ecu flash into older Zs?