The BMW Z4 is one of those cars that has a few bhp options when you purchase the car, but the engine is exactly the same! The Z4 18i, 20i and 28i all use the 2.0 N20 engine, with BMW limiting the power in the software in the 18i and 20i. This particular example is the 156 bhp 18i which means you can experience the biggest jump in terms of performance.
Unfortunately, the car only had a tank full of 95 ron so we couldn't achieve the highest power and torque we would have like, but we're going to see the car again with good fuel to finish writing the software.
Power gained: 106 bhp
Torque gained: 120 nm @ 6,300 rpm