anytime you "reengineer" your car, things change... for better or worse
when you put bigger brakes only on the front wheels on ANY car, the brake bias will shift to the front as braking power has increased in the front... it may make control more difficult because the proportioning valve is not meant for such a disproportionate brake size and the front wheels will lock up more easy, which means easier to understeer the car and/or run into something
similarly, if you upgrade only the rears (no one does that), then your car becomes more tail happy when you brake... its like yanking the ebrake while driving down the road... some drift cars OTOH are setup to have more brake bias to the rear so that it CAN start a drift more easily
ideally, you upgrade all the brakes (like I did with the EDM brakes) and your brake balance stays pretty much the same and overall braking improvement because ALL 4 wheels does the slowing down, not just the fronts!