[Merli]

Generally, bigger brakes don't give you a performance increase by way of better stopping distances. They give you better performance by way of increased heat build up resistance and increased heat dissipation.

If your brakes can lock up your wheels (i.e. activate ABS), then your brakes aren't the weakest link.

If you want to increase braking performance (shorter stopping distances), put on stickier tyres (e.g. R-Compounds, Semi-slicks or Full racing slicks).

Of course NOW, with better tyres, you will be working your brakes much much harder, as they will generate a lot more heat in the rotors, pads and fluids, so then NOW you may benefit from uprated calipers, rotors and pads.