I take it the car has the factory infinity system? If it does, you'll have to run new speaker wire from the deck to the amp location. Also there is no switched power in the harness, so you'll have to run one from either the fuse box, or you can pick it up at the cig plug. That is if your cig plug loses power when you turn the car off. As for finding the vss in you car I'm not sure on that one since I've not done any sort of navi in a magnum.