The 6 pot Tarox brakes are working well for me.

I'm running the 280mm disc inside 15" rims.

(I've got them on a MK1, but it's using MK2 16v uprights.)

I gave up on he stock style single and dual piston calipers as I kept getting pad knock off no matter what I tried. Now pedal feel is consistent through out a race.

Just watch out for clearance on the back side of the wheel with any of the big brake kits. It can be hard to find wheels that will clear the calipers.

Tarox | High Performance Brakes