428i
N20

All three. The F32, F33 and F36 share the same N20 engine, ECU and ZF 8-speed, so every stage on this page applies across the range. Samuel tailors each file to the specific car submitted, so a convertible driven gently and a Gran Coupé used hard will not receive the same calibration even at the same stage.

Three supporting parts: downpipe, intake and intercooler. With those fitted the standard turbocharger can support 320 bhp and 450 Nm, up from Stage 1's 280 bhp and 400 Nm. Send Samuel the exact brands and specs when ordering; the file is calibrated to the hardware that is genuinely installed rather than to an assumed parts list.

It needs the fuel the map was written for. Tell Samuel what you run and the calibration is matched to it: super unleaded allows the most aggressive safe timing and the full advertised figures, while a 95 RON file trades a little peak output for margin. Mixing a super-fuel map with supermarket 95 is the one thing to avoid.

Production ended in 2016, so original manufacturer cover has lapsed on every 428i; what remains is typically a used-car or extended warranty, and those policies differ on modifications, so check yours. Samuel's calibrations stay inside the N20's mechanical tolerances, and the tune can be flashed back to the retained stock file before any warranty assessment.

For headroom relative to cost, yes. Stage 1 adds 35 bhp with no hardware spend, and Stage 2's 320 bhp takes the 428i past the factory output of a standard 435i for far less money than the six-cylinder car commands. The N55 ultimately stretches further, but on pace per pound the tuned four-cylinder makes the stronger case.