alright peeps, just topped my oil up with castrol magnatec which is great. but i have over filled.
will this affect the car? its over the MAX mark by about 6mm

I'm not too sure what happens but I think it can do harm to your car...

hopefully someone can give you advice on what's best to do mate, I'd hold off driving it until someone confirms what to do or says it isn't a problem..

Yes, you definitely should drain some out asap, there are various problems that it can cause such as the oil seals to leak. It is something that you need to be quite careful with, as the amount it says to fill with in the manual is pretty vague, simply saying it takes between a half and one litre of oil to fill from min to max.

I might be wrong, as I'm not exactly sure about this with the ST, but I thought that over-filling an engine with oil would bring the oil level in to dangerous contact with the crankshaft causing a 'churning' effect, thus throthing the oil (which in turn will affect the oil's circulation). The last thing you want is a loss of oil pressure in an engine. Major problems will result.