A bit of research shown G20 with B48C engine has turbo charger with code 11658662071. Nobody is really offering this turbo yet. Older version 11658662070 was used in many BMW cars in the past. I found only visual difference on the air intake part.
For B48D engine (320i and 330i) is used turbo 11658662073 resp. 11659845815. Therefore I believe this 320i can be unlocked to 330i by ECU flash.
Here are pictures what I think is the limit for B48C. Exhaust gas enters the turbo's turbine through the inlet port which is significantly smaller for B48C. Not sure how much is this smaller port limiting turbo efficiency. I would assume in higher load when engine pushes the hardest the most exhaust gases are produced... my question for turbo experts would be how much Wastegate valve kicks into action and diverts exhaust gases to protect turbine even with small B48C's inlet ports when turbo boost enhanced (piggy bag / ECU flash). I don't think this is super limiting though
