I ran it under the car, on the passenger side, in plastic wire loom, wireties at 6" intervals, attached to existing lines(brake, gas?), and came in the trunk thru existing hole, using a plastic snap grommet to prevent chaffing of the wire, then used a bolt to ground the battery to the frame.

Sold 1998 Contour LX 13.868 sec 1/4 mile time. Two years of rental cars, seriously. Holding out for 07 Cobra Mustang.