Alpina B3 S brake imbalance

[Mastertech1]

I have my E46 B3 S in at BMW dealer where it has failed the MOT on brake imbalance between the OSF and NSF and also the rear brakes are producing more brake for than the front. I have had them bleed the brakes plus flush the DSC which has helped slightly but not enough to pass it. The person I bought the car off had replaced the front /rear discs and pads not sure if genuine. The garage admit they haven’t seen anything like this before, and can’t see anything wrong with the braking system.
I’d be grateful to know if anyone has had or heard of similar if non genuine pads and discs have been used .

[Fast3000]

Not heard of this specifically before. My guess is its a e46 issue rather then a Alpina one. You did the right things already and it's usually a process of elimination. I had my calipers rebuilt with new pistons and rubbers last year... This did make a significant difference on the pedal feel. Considering these cars are coming to 14 years old plus...have you looked at if this?