what do you mean by better braking though?

what is the problem with your current brakes, that makes you think that you need different / bigger ones?

it may not be brake related at all, or could be easily solved with a change of fluid or pads for example.

to answer your question, yes of course you can use the same calipers on a bigger disc, as i have on my 330's. the pad area may not be perfectly matched to the inner and outer radii of the larger disc, but generally the whole pad area will be covered. the advantage is that as the disc has a larger surface area, it can dissipate the heat quicker and resist fade. my 330's are also much thicker than std discs, which also helps.

to do so, you need to space the caliper further out, and make sure that it will clear the wheels. the std calipers are quite large compared to brembo, AP etc, so there is a bit of a disadvantage there. i made up my brackets myself as they needed to go further out from the strut, and further out from the centre of the car (depending on the rotor bells). I also made thicker spacers between the 2 caliper halfs for the thicker discs.

as the pistons in the caliper are matched to the master cylinder, you keep the same pedal feel. if you went to a caliper with a smaller overall piston area, your brake pedal would need to travel less to get the same clamping force, and vice versa with ones with a larger overall piston area (maybe 6 or 8 pots or whatever).