Alive Tuning wrote:

Bigger discs give more surface area, for larger pads to bite onto. The larger the disc diameter, the greater the stopping power.

I use the Hi-Spec brakes using the standard (ancient) defender servo, and the pedal feel is superb. The choice of pad material makes a difference to pedal response too.

If we put bigger calipers and discs the feeling and the performances change completly in better, but if we put a 4 pot billet front calliper conversion (like the one you are preparing) and we do not change discs and pads, the friction surface remain the same. In that case the fading can occur in the same way.
Hi-spec pads reduce this symptom, also hi-spec discs, but the downside of this change is the price  Matteo
Defender 110 Td4 SE MY 09