Hi finest upgrade is high carbon discs that are drilled on the front and just plain high carbon discs on the rear pad wise either Brembo or ATE, the biggest bonus will be achieved by changing the brake fluid using Comma dot 4 ESP, I used drilled ATE front and plain ATE discs on the rear of my cab the fronts now need changing but they have done 70k, grooved discs just eat pads and get bits of crud stuck in the grooves which wear the discs at an accelerated rate with no real benefit in braking performance, on the other hand drilled discs cool quicker as well as dissipating water on the discs during wet weather twice as quickly.
Steve.