To paraphrase an old song, plugs and wires go together like a horse and carriage. You shouldn't change one without the other. And when you do change them, you should make sure they were made for each other. Wires and plugs are just one link in the entire ignition system, so any changes have to be carefully coordinated. Mismatching plugs and wires can mess up your ride more than a little bit. Upgrading to high-performance spark plugs and low-resistance plug wires can net you more mpgs and better performance. While you are at it, you might look into putting in high-performance coils and ignition boxes. They will help your engine get more power out of your gasoline.