Do a search on here mate, before this turns into 20 pages of ramblings.
For my 2p's worth, I do use Optimax. There are people on here who seem to think that the first time they fill up with 'the good stuff', their car will turn into a rip snorting monster, it changes gear faster, the turbo whistles louder and they suddenly get torque steer in 5th. None of these will heppen.
After 2-3 tanks you might notice a slight improvement in smoothness, or it might feel a little more keen, but thats it.
Running it on a decent regular unleaded will do it no harm either. Your ECU will sort it all out.