Grant, you understand engine design, I don't - but I'll try my best. Maybe someone can jump in and provide better explanations

  • in total 7 throttle valves; 3 per cylinder bank plus a common one controlled by 3 motors
  • steel exhaust system instead of titan 
  • secondary air pump to add air to the exhaust stream to meet regulations
  • OPF has before and after pressure sensors
  • "the OPF is like a cork in the exhaust stream"