j spec

working on a friends car. got the harness in just working on plugging the interior side of it together. now the question: si harness has one extra 4wire plug close the ecu that the dx harness didn't have there for it doesn't plug up. also si harness does not have a 2wire plug that goes to the climate control that the dx harness does have(i think its for the lighting) i haven't got the driver side entirely plugged up either so wondering what else to expect? also is this a common thing to do to these cars or do most people just run the extra injector wires. would it be easier to swap the whole dash? thanks for the help