G-POWER has built its reputation over four decades tuning BMW’s M engines, but its newest package skips the M badge entirely and goes after the B58. The 3.0-liter turbocharged inline-six has powered a wide range of non-M BMWs for more than ten years, and cars like the M240i, M340i, M440i and Z4 M40i have built a following among enthusiasts who like what the engine does without needing an M3 badge to justify it. G-POWER’s answer is the GP-480 Performance Upgrade, a package built specifically for the G42 M240i, G20/G21 M340i, G22/G23/G26 M440i and G29 Z4 M40i.

The headline number is 480 hp, up from the B58’s factory output that tops out in the mid-300s depending on the model. G-POWER pairs that with a claimed top speed of 300 km/h (186 mph) and a stationary exhaust noise reading of up to 100 dB, which puts the exhaust note on par with what you’d expect from a track-prepped car rather than a warmed-over commuter.

The upgrade isn’t just a software flash. The GP-480 Performance Software is bundled with an HJS downpipe, the G-POWER DEEPTONE rear silencer with carbon-fiber tailpipes, GP charge pipes and a GP intercooler. That combination addresses the usual bottlenecks on a tuned B58: exhaust flow, charge cooling and turbo response, alongside the calibration work that ties it all together.

G-POWER says every component is available individually or as a complete package, and all of it is supplied in road-legal, registrable form, which matters for anyone tuning a daily driver rather than a track-only car. The conversion itself happens at G-POWER’s headquarters in Gachenbach, Bavaria, where the company installs the hardware, runs custom calibration on its in-house dynamometer, and finishes with an inspection and certification process before the car goes back to its owner.

G-POWER hasn’t published pricing for the GP-480 package at this stage.