I had considered thinning my harness after engine swap and was glad I didn't remove wires after because they can be used for other functions.I use the power wire from the evrv egr plug for my heated o2.saved me running any wires.also the Grey wire for egr can be used for wide band o2.just remove from ecm connector.it's nice having wires already in place for other stuff.I taped what is not in use to the harness for possible later upgrades etc.no wire to run or holes to poke.