Sideways, negative terminal down. Only use the metal bracket, not the plastic battery cover. You will need to make a 6" extension for that small ground cable, just bullet male and female. I shimmed the side of the box w/ some foam to keep the battery tight. My only complaint has been tires, the scorpion AT was my least favorite-go figure. I got crap mileage out of them, I like the ST much better as a road tire. and my un-do's have been windshield, fender, and handguards trying to find the combination that minimizes turbulence and maximizes protecton.