I have concluded I have two pre cats. Radiator side bank 1 and firewall side bank 2. I needed to know the easiest way to loosen the bolts. Pb spray or heating the bolts up. The one I am replacing is the one on the firewall.
Warm and give a good spray, use a good fitting single hex socket and a suitable lever, pull firm and even pressure and it should come loose. When it starts to move pull back and forward a little as this will help loosen any rust and keep the spray up as well.