Just following up - I now have my Dunlop SP Sport 01's fitted on the front (conti SC3s on back) and my god what a difference. Since owning this car (nearly 3 years now) Its had very poor handling. Wandering all over the road , unstable at speed, poor handling.
It originally had a set of cheapo chinese tyres on, so I first had a set of Falken FK452s, then more recently Falken ZE912s. It has been to WIM 3 times for setup, had new wishbones, steering box adusted and lots of fidding but the handling was still crap.
Now a new set of tyres and bingo its fantastic. Ok its not pin sharp (but it is an omega) but it doesnt wander or tramline any more, it corners crisply and rides more smoothly. No real road noise to speak of either (well no more than previously anyway). Falkens clearly dont suit the Omega.
Oh and the rather worrying shush-shush-shush noise I was getting from the front left has also gone now too. So it wasnt a wheel bearing after all, just the tyre.