Originally Posted by Chas

Do you have your heart set on Brembo calipers? They will reduce the unsprung weight but not necessarily improve the performance.

In the vast majority of cases the proven Sierra Cosworth hybrid setup (4WD calipers with 2WD discs) or Mondeo/ST170 setup will suffice for almost all cars out there. Neither will require you to change the master cylinder either ; My S1 stops very very well on the Cosworth setup.

I think the Cosworth setup can take almost any 15" wheel whereas the ST170 setup can only take a selection of 15" wheels (maybe more with shaving the calipers) and all 16" wheels. You may also have to drill out the hub carrier holes further for the Mondeo calipers IIRC.