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Spool Performance FX-400X high-pressure fuel pump for BMW B58 Gen2 — G-chassis
SPOOL PERFORMANCE

Spool Performance FX-400X High-Pressure Fuel Pump (Stage 4) — B58 Gen2 (G-Chassis)

$3,035.00

Spool Performance FX-400X — the flagship "Stage 4" high-pressure fuel pump for the Gen2 B58. It runs the same 350 bar (5,000 psi) as the FX-350 but moves about 20% more fuel across the whole delivery range, for builds that have outgrown the FX-350.

What it supports

With Spool's Gen2 DI injectors, roughly 1,100 whp on gas, 900 on E50, 800 on E85; add the high-lift exhaust-cam fuel-lobe mod and about 1,200/1,050/900. Single pump, plug-and-play, lifetime warranty.

Where it fits in the build

High-pressure (DI) side; requires an upgraded low-pressure in-tank pump and a matching calibration. We tune the engine to the fuel system.

Options

Spool offers a wireless ethanol-content analyzer and a 10-micron inline filter as add-ons — tell us if you want either specced in.

Fitment

Gen2 B58 (G-chassis) — M340i (G20/G21), M440i (G22/G23/G26), M240i (G42), Z4 M40i (G29), and the rest of the Gen2 B58 range. Confirm your chassis in the selector.

Sourcing fueling with the tune? The Fueling Kit — B58 bundles the matched pump + calibration for 8% under à la carte.

Fits engine B58
Fits chassis G20 · G21 · G22 · G23 · G26 · G29 · G42
Category Fuel
Manufacturer Spool Performance
What this is

A Part Recalibration is one focused revision built around the part you just bought. We take logs on your car as it runs now, on your current tune, then make a single full revision so this specific part delivers what it should. Hardware only does its job with a calibration shaped around it.

We bundle that tuning with the part right here, whatever brand the hardware is. If you want a fresh start across all your hardware, a Full Tune is the step up: a new base map, three revisions, and a written report.

This is a bootmod3 calibration. We tune through your own active BM3 license, so you'll need bootmod3 active on your car to load it.

Ships from Boca Raton, FL.

Step up to a Full Tune?

You've added a Part Recalibration to more than one part. At that point a complete tune does more for you: a Full Tune lays down a fresh base map and three revisions so all of your new hardware is dialed in together, with a written report at the end. We can roll your recalibrations into one Full Tune for $395 — below our standalone Full Tune, which starts at $495 for a four-cylinder and $595 for a six.

The Full Tune is a bootmod3 calibration — it loads through your active BM3 license, the same one you confirmed for the recalibration.
WHY WE SHIP SPOOL PERFORMANCE
Spool Performance builds high-pressure fuel pumps for the builds that have outrun what the factory pump can flow. On a big-power direct-injection BMW, fuel supply is often the actual ceiling, and the engine will pull rail pressure long before it runs out of airflow. We ship Spool because their HPFP upgrades are aimed squarely at that ceiling, restoring the supply margin a high-output calibration depends on. This is upper-end fueling hardware — the part you add when the dyno shows the pump, not the turbo, is what is holding the number back.