The TOWMA High-Performance Downpipe for the BMW M5 G90/G99 was developed for the all-new 2025+ M5 with the S68 4.4L V8 bi-turbo engine. This downpipe maximizes the performance of the powerful V8 with free exhaust flow, an aggressive sound, and a perfect fit—an essential upgrade for the new-generation M5.
Advantages
- Maximum flow — free diameter for minimum restriction
- More power — 20-30 extra hp with ECU/TCU tuning
- Faster turbo response — less backpressure, faster spooling
- Aggressive V8 sound — deep, powerful tone
- OEM+ fit — direct mounting without modifications
- T304 Stainless Steel — High-performance stainless steel for extreme temperatures
- TIG welded — perfect welds for optimal strength and flow
- Optional heat shield — extra thermal protection
Material & Construction
The TOWMA downpipe is manufactured from high-quality T304 stainless steel , specially chosen for its excellent heat resistance and durability at the extreme temperatures of the S68 V8 bi-turbo engine.
The system is fully TIG-welded for optimal strength and flow. The free-diameter pipework with no internal restrictions ensures maximum exhaust flow.
Available in two variants:
1. Catless (without catalytic converter):
- Maximum flow and performance
- Loudest, most aggressive V8 sound
- Maximum power gain (25-30 hp with tuning)
- Not MOT-proof in the Netherlands
- For track/export use only
2. High-Flow Sports Catalyst (200-cell):
- Balance between performance and emissions
- Sporty V8 sound, slightly less loud than catless
- Good power gain (20-25 hp with tune)
- Possibly MOT proof (depending on inspection)
- Suitable for daily use
Optional heat shield:
For additional thermal protection, the downpipe is optionally available with a heat shield. This protects surrounding components from the extreme heat of the turbos and downpipe.
Performance & Sound
Capital gain:
- Catless: +25-30 hp with ECU/TCU tuning
- High-flow cat: +20-25 hp with ECU/TCU tuning
- Without tuning: +8-12 hp (only due to better flow)
- Total power with tune: 750+ hp possible!
Sound character:
The TOWMA downpipe allows the S68 V8 to reach its full potential:
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Idle: Deeper, more present V8 bass
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Acceleration: Aggressive turbo whoosh and wastegate flutter
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High revs: Loud, race-inspired V8 sound
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Deceleration: Pops and bangs (with tune)
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Downshifts: Aggressive backfire and crackling
Note: Catless is significantly louder than high-flow cat. Consider your neighbors and daily use!
Installation & Assembly
The downpipe is designed for direct mounting on the original BMW mounting points.
Installation steps:
- Lift the M5 and place it on the lifting bridge
- Remove original downpipe (3 bolts top, 2 bolts bottom)
- Install new TOWMA downpipe with supplied gaskets
- Install optional heat shield (if ordered)
- Tighten all bolts to specifications (45-50 Nm)
- Check for leaks upon initial start-up
- Reset error codes (if present)
Installation time: 2-3 hours for an experienced BMW specialist
Recommendation: Professional installation by an authorized BMW M specialist or tuner is STRONGLY recommended.
ECU/TCU Tuning: For optimal performance, ECU and TCU tuning is highly recommended. The downpipe alone provides 8-12 hp, but with tuning it can add 20-30 hp. Popular tuners: Bootmod3, MHD, Evolve.
Compatibility
Suitable for:
- BMW M5 G90 (2025+) — sedan
- BMW M5 G99 Touring (2025+) — wagon
- Engine: S68 4.4L V8 bi-turbo (727 hp standard)
Not suitable for:
- BMW M5 F90 (2018-2024) — previous generation
- BMW 5 Series without M
Note: This is ONLY for the new G90/G99 M5 (2025+). Check your VIN before ordering.
Technical Specifications
| Characteristic |
Specification |
| Brand |
TOWMA Carbon & Performance Parts |
| Product |
High-Performance Downpipe |
| Material |
T304 Stainless Steel |
| Welding method |
TIG welded |
| Diameter |
76mm (3 inch) |
| Variants |
Catless or High-Flow Cat (200-cell) |
| Heat shield |
Optionally available |
| Fit |
OEM+ direct fit |
| Suitable for |
M5 G90/G99 (2025+) |
| Capital gains |
20-30 hp (with ECU/TCU tune) |
| Installation |
Plug and play, no welding |
| Warranty |
3 years on construction and fit |
| Price |
€1,399 |
Maintenance & Warranty
Maintenance:
- Check flanges for leaks regularly
- Inspect gaskets annually
- Check heat shield for damage (if fitted)
- Clean the outside with stainless steel cleaner for a shine
- Check mounting bolts for tightness
Warranty:
TOWMA offers a 3-year warranty on construction, fit, and finish. The warranty covers manufacturing defects, leaks, and fit issues. Damage due to improper installation, accidents, or misuse is not covered by the warranty.
Note: Installing a downpipe may affect your manufacturer's warranty. Check with your dealer before installing.
Frequently Asked Questions
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Do I need ECU/TCU tuning? Not required, but highly recommended. Without tuning, you'll gain 8-12 hp, with tuning, you'll gain 20-30 hp.
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Is this MOT-proof? Catless is NOT. High-flow cat is possible, depending on inspection.
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How loud is this? Catless is very loud. High-flow cat is sporty but more bearable for everyday use.
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Will I get a check engine light? Possibly. This can be resolved with ECU tuning or O2 sensor spacers.
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Do I need the heat shield? Recommended for extra protection of surrounding components, but not required.
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Will this fit my F90 M5? No, this is only for the G90/G99 (2025+).
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Can I install this myself? With basic tools and experience, yes, but professional installation is recommended.
Free shipping in the Netherlands on orders over €50. Direct delivery from stock.
