If its a street car ya really dont gotta worry bout killing the alt power with the shut off. Think about it, if your in an accident who's gonna think to look for a kill switch? I done mine like Goody did. Mounted the battery in the trunk. 1 fat ground cable straight to the frame through the trunk pan. Ran the positive to the front and put it where the normal + cable woulda went and ran a short one off the same relay post to the big starter terminal. Also made a fat ground to go from the block to the frame rail in the front. Works great, never a voltage or charging issue.