Ok I was looking at another thread and people were talking about gearboxs, anyway in the future I am looking to put a 2.5V6 into my astra.

I have never been a man for top end speed and more into getting there (aceleration )
When I spoke to courtny they said they would fit a F23 Gearbox into the car now if i was to fit a smaller ratio gearbox (like a F20 or even F18 ) to improve the aceleoration and lower top end (120MPH say) would the gearbox be able to handle the power of a V6
or would there be anyway in which I could use a F23 but improve other parts