[dfwright]

The instructions given are pretty clear. cut out the white box from this instruction page, then from the inside of your firewall, under the dash, line up the right and top lines of the cutout to the existing hole, and trace the cutout. You'll end up cutting the left side and bottom edge of your existing factory hole out a little wider, as well as rounding out the radius the top right corner. mark the hole spots and drill as described.