The B58 makes easy power because BMW built it with headroom: a closed-deck block, a forged crankshaft, a twin-scroll turbo and a water-to-air charge cooler. A stock M340i, GR Supra or G42 M240i will take a Stage 1 tune with nothing else and gain a large chunk of horsepower. The trick is doing the mods in an order that keeps the engine happy as the power climbs. This is the path we recommend.
Stage 1: Tune and plugs
Start with the tune, because everything after it is really about supporting the tune. You have three good options and we sell all of them: the JB4 piggyback (plug-in, no ECU flash, easy to remove), the MHD Super License (flash tune with everything stored on your phone) and bootmod3 (flash tune with cloud-managed maps and wide custom-tuner support). Our JB4 vs MHD vs bootmod3 guide walks through the differences.
At the same time, fit a fresh set of NGK 96206 plugs (or the 94201 on a Gen 1) gapped for boost. Misfires under load on a freshly tuned B58 are almost always plugs, and it is the cheapest part on the list.
Stage 2: Charge pipe, downpipe, intake and cooling
Once boost goes up, the factory plastic charge pipe becomes the weak point. Replace it before it fails: the Mishimoto B58TU charge pipe, the Active Autowerke charge pipe and the aFe BladeRunner are all aluminum, and the BMS charge pipe and BOV kit adds a proper blow-off valve. Our charge pipe failure guide explains why this matters.
A downpipe is the single biggest bolt-on gain on a tuned B58 because the factory catalyst sits right at the turbo outlet. For a street car choose a high-flow catted pipe such as the Active Autowerke catted downpipe or the Evolution Racewerks Sports Series; catless downpipes are for off-road and competition use only, and either type needs a matching tune map.
An intake adds a little power and a lot of sound. The BMS billet intake and Injen Evolution cover the Supra and Z4, while the Dinan carbon intake and aFe Momentum GT cover the G20/G22/G42 cars.
Finally, cooling. The B58's water-to-air charge cooler heat-soaks on back-to-back pulls, and the fix is a larger front heat exchanger: the CSF heat exchanger with rock guard, the Mishimoto heat exchanger for the Supra and Z4, or the AMS heat exchanger for the M340i. A catch can is cheap insurance for the intake valves at this stage too.
Stage 2+: Fuel for E85
Ethanol is where the B58 really wakes up, but the factory direct injection system runs out of flow first. The step up is a high-pressure fuel pump upgrade such as the Dorch DS25 (Gen 1 and Gen 2 versions are different) and, for higher ethanol blends, a port injection kit. Read our port injection explainer before choosing, and plan on a custom tune at this point.
Stage 3: Turbo
With fueling and cooling sorted, a drop-in turbo upgrade from Pure Turbos is the last big step. Nothing in Stage 3 works without Stage 2 and 2+ already in place, which is why we list the required supporting parts on every turbo product page.
A note on Gen 1 vs Gen 2
Charge pipes, fuel pumps, plugs and tuning hardware differ between the 2016-2019 Gen 1 B58 and the 2019+ Gen 2. Our Gen 1 vs Gen 2 guide explains how to tell which you have, and every product page lists the chassis and years it fits.