Hi Tom, assuming you are not wiring a DD2, there is only one ground wire to be dealt with (the long one). The longer of the two wires attaches to back, inside cylinder head nut. Be sure when you attach it to make sure there is no tension on the wire. Give it as much of a loop as possible and be sure to zip tie it to the bracket so it can’t swing around, other wise it can break and ruin your day. The new harness grounds to the bracket itself, which is a big improvement. And yes, the unused wires can just be ties or taped back.