Genuinedealz is the ticket for wiring. Visit their site and price them out. There's a voltage drop calculator there also. Get the "add-a-battery". I moved mine under the console and added a positive and negative post mounted to transom, engine leads go there and new cables to console go there. The third is the additional charging lead I'm not using. If there's room in your rigging tube it's not that bad to pull new one's just make sure the length.
