brake pads

If I do this upgrade all I need is the new 300mm disc and the bigger carriers right? I wondering if the callipers are the same then what happens to the brake pads? Do I buy the 300mm version of the brake pads because if I buy the old ones won’t I have the same braking because the same amount of...

I bought my 1996 1.9L Z3 a year and a half ago (used obviously) and at the time had the front brakes replaced. I can't remember if the mechanic replaced the calipers, but the pads and rotors were replaced. I recently went to a track event and now the brakes squeak just before I come to a stop...