Milltek Sport BMW M3/M4 (G8X) GPF Bypass
Free up exhaust flow and unlock a sharper, more characterful sound on your BMW M3/M4 G8X with Milltek’s GPF Bypass. The GPF (gasoline particulate filter) sits in the exhaust and traps fine soot. It also adds back pressure, which can hold the engine back. This bypass removes the GPF section, letting the S58 breathe more freely.
Why this matters
- Reduced back pressure for smoother, more responsive acceleration.
- Stronger, deeper exhaust tone that suits the M car character.
- High quality T304 stainless steel for durability and corrosion resistance.
- Designed to fit with OEM downpipes and either the OEM or Milltek GPF-back exhaust.
Sound options
Choose Resonated for a more refined tone with reduced drone on the motorway. Choose Non-Resonated for a louder, more aggressive sound. Power potential is similar – the choice is mainly about noise level and comfort.
Fitment
Made for BMW M3 and M4 G8X models with the S58 3.0 twin turbo engine. It installs between the OEM downpipes and the GPF-back section, and is compatible with either the factory GPF-back or a Milltek GPF-back system.
For grouped guidance: fits popular BMW M3/M4 G8X applications. Please use the vehicle lookup on our site to confirm, or check the Vehicle Fitment tab for full details.
Options and SKUs
| Bypass Type | Exhaust Pairing | SKU |
|---|---|---|
| Resonated (Quieter) | OEM Downpipes + OEM GPF-Back | SSXBM1195 |
| Resonated (Quieter) | OEM Downpipes + Milltek GPF-Back | SSXBM1193 |
| Non-Resonated (Louder) | OEM Downpipes + OEM GPF-Back | SSXBM1196 |
| Non-Resonated (Louder) | OEM Downpipes + Milltek GPF-Back | SSXBM1194 |
What to expect
With the GPF removed, you can expect a crisper throttle response and a stronger, more engaging sound. Any power gain depends on the rest of your setup and tuning. For best results, pair with a quality GPF-back exhaust and suitable ECU calibration.
Important notes
For off-road or motorsport use only. Not legal for road use in the UK. Removing the GPF affects emissions and MOT compliance. A check engine light will occur unless the GPF is correctly coded out in the ECU. Professional installation and appropriate software are recommended.




