I just got back from CZL after flying the RV12 Honda Viking for 1.8 hours.  The fuel line going from the fuel manifold to the engine is under high pressure, about 45 PSI.  The fuel injection line is 5/16 and purchased from local auto store.  Fuel injection requires high pressure from the pumps to the engine.  You have two clear plastic fuel filters which take low fuel pressure before the fuel pump.  There is a high pressure fuel filter just before the fuel enters the engine.  The Rotax engine is carbureted and uses low pressure.  Ron Russ