Remote tuning services are perfect for the X1 20d. The B47 engine in the F48 responds very well to a remap. Expect around 200-210hp from the 150hp version, or 230-240hp from the 190hp version. TempaDrive offers remote tuning within your budget. The process is simple - they send you an OBD tool, you read the ECU, send the file, and flash the new map back.
I tuned my wifes X1 20d (190hp version) and its a completely different car now. 240hp and 480nm makes it feel like a proper SUV instead of an underpowered crossover. Highway overtaking is effortless now. Fuel economy stayed about the same because you dont need to floor it anymore.