I have just been pondering what I have put above - and wondered that I may be able to significantly help myself by reducing my rear wheel diameter down to 16". This would reduce the Moment of inertia by around 10%, so the car would accelerate better, whilst also effectively reducing the gearing. This should help me get a lot more acceleration, which should be great since I am no where near reaching full revs in top.
Has this been done on an S2 before? What is the point of the rear wheel being a larger diameter - I assume its a styling thing, as the change in footprint would be minimal?