I recently beat Zico, I did it with 3 BR's.

Leading up to the good lap i managed to Br onto the overpass constantly, but on the good lap I failed but still managed to equal zico's time.

Make sure you take all the corners tight, but the place where you can really make time up is with a very good line on the first BR: Turbo up the small bump, BR and aim for the right hand side of the track, if you can keep in a straight line from the first BR into the next one then it could be the deciding factor.

EDIT: Don't know if it is just me, but it seemed easier to do since the update and Zeus!