Hey,
I have the same interest about watching the weight of my car, and although for different reasons to yours, it would have the same benefit. While i dont have MX83 brakes, I have got the upgrade and here are the results:
Single R33 caliper with all pins, shims, pads with decent meat - 4.0kg
Single DBA standard replacement BA Falcon rotor - 9.0kg
So total upgrade (not counting hoses and centre ring) - 26kg
Look forward to anyone who puts up the MX83 as reference (although my car has slightly bigger brakes to start with so would stand to save a little more or gain less).
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