I fitted a wilwood bias valve to mine and it still didnt knock enough power out of the rear to get it right!

This ended in a high speed spin at 2am on the A12! Very dangerous! Stick with the drums! If not, a peddle box (which I now have fitted) is the only way to get it right.

Lots of people run discs and have no problems, its only when you need to REALLY brake hard that you will discover you have a problem.

If you do use discs make sure you fit the shitest cheapest pads you can! Good quality high friction pads will only make the problem worse. Back brakes do less than 10% of the braking on a FWD car.