Jez,
The OEM recommended settings have wide tollerences, however these tollerences can be exceeded to suit your style of driving and in particular if you are a weekend track warrior.
What is one man's food is another man's poison.
However best not to go silly as you will experience excessive tyre wear and the secret is getting the balance right between comfort, handling and tyre wear.
Thrust angles are also important.
Front and rear caster, camber and toe kits are in stock and good to go if required.
Alex