I have a Brey Krause Harness bar and mounts for six-point Simpson Belts both sides. The cut you mentioned was a small matter, just widening a slot already in the molding for the factory belt. The molding snaps out then snaps back in after the small mod. The mounts bar mods and belts took me 2 hours. The directions say you can do it by loosening the seats and tilting them. I found it easier to just take the seats out (Watch the electrical connections underneath) do the mods and install the mounts and put the seats back in. My neihbors thought I was nuts, buying a $50,00.00 car then "ripping" it apart the next day!