The B58 3.0L turbo six is one of the best engines of the last decade. It's strong, smooth and incredibly responsive to modifications, and you'll find it in the BMW M140i, M240i, 340i/M340i, 440i/M440i, 540i, X3 and X4 M40i, Z4 M40i and the Toyota GR Supra 3.0. Here's the order I'd modify one in.
1. Cold air intake
An intake is the easiest first mod. It bolts on in under an hour, adds induction sound and turbo noise, and lets the engine breathe more freely. On its own the power gain is modest. The real value is that it sets you up for a tune and more flow later.
- F-chassis B58 intake: M140i, M240i, 340i, 440i
- G-chassis B58 intake: G20 M340i, G22 M440i, G42 M240i
- GR Supra A90/A91 3.0 intake
- Z4 G29 M40i intake
2. Downpipe and tune: the big one
The factory downpipe is the biggest restriction on the B58. A larger downpipe paired with a tune is where the serious gains are. Turbo spool gets noticeably sharper and midrange torque jumps. For a car that's driven on the road, choose the high-flow catted version. Catless downpipes are off-road and competition only, and they aren't road-legal in Australia (see our catted vs catless guide).
Mechanic's note: don't fit a downpipe without planning the tune. Tuned B58s also appreciate fresh spark plugs, gapped correctly for the extra boost.
3. Exhaust: for the sound
Once the power is sorted, a valved exhaust gives the B58 the voice it deserves: quiet when you want it, loud when you don't. Valved systems let you keep the car civil on the daily drive.
- B58 catback or full exhaust: G20 M340i, G22 M440i
- F30 340i full valved exhaust
- GR Supra full valved exhaust
The short version
Intake first for the easy win, then downpipe plus tune for the real power, then an exhaust for the sound. Browse the full range in our BMW collection and GR Supra collection.
Not sure a part suits your car? Email andrew@clippingpointco.com with your year, model and engine before ordering. As a qualified mechanic, I'll check fitment for you.