I have this leak too. Baffled me until I realized it was the bushing. I can't find a replacement bushing part for our cross member, so I'll either get a Spec B one or a plain LGT one. But, according to opposed forces this part is the replacement for the whole assembly:
41310AG02B
EDIT:
It appears the STI guys are replacing just the bushings in the assembly with Whiteline KDT905, which is listed as compatible with our cars.
http://www.whiteline.com.au/product_..._number=KDT905
http://www.iwsti.com/forums/gr-suspe...at-normal.html