dont know if someone does these for the Astra, but i have heard good reports on them when used on "cough" fords "cough"! lol
dont know what they are called, but its basically a thick bar that replaces the radiator suport. then there are two bars (with rose joints) that go back the the lower wishbones. there is also a third bar that basically suports the rad support that runs back to the bulkhead. you then basically tighten the bars to the wishbones until tight.
from what i read this helps quiet a bit with trcation off the line and coming out of corners. basically from what i remember it helps keep the wheel dynamics a little bit tighter during launches or exits or corners.
i will try and get some more info on it, but im moving house so might take a bit of time.
what do you guys think about this??