BMW Questions? Ask a BMW Repair Expert for Answers.
With any carburettor change as a performance enhancement, if the engine can run full power in each gear, say 2nd through 4th at wide open throttle and not starve (run out of fuel), then the pump should be adequate.
If the car lays over in 3rd gear at 5500+rpms then the pump needs to be upgraded.
If the car is making about 20% more power, it should be ok.
I hope my advice as above has given some guidance to you.
I've been a mechanic/hot rodder/tuner for many years.