Grail exhaust system 3.5 inch suitable for BMW M4 F82 / F83 without OPF (S55) – Valve system

The most uncompromising system for the S55 – 3.5 inches, without OPF, brutally loud

If the 3-inch system is right for your MWhile the 4 was already a step above the standard, the 3.5-inch GRAIL is on another level entirely. Specifically designed for M4 F82 Coupé and F83 Cabriolet without gasoline particulate filters, designed for maximum exhaust flow and uncompromising sound. This system extracts the maximum power from the S55 biturbo out, what BMW M who had technical confidence in him – without filters, without restraint, with the full presence of an inline six-cylinder engine.

And the best part: despite its brutal sound, the system remains fully legal and registration-free within the EU thanks to ECE type approval. Ready to drive immediately after installation, no TÜV appointment, no registration bureaucracy.

Handmade in Germany, entirely from L304 stainless steel. The premium choice for M4-drivers with a non-OPF setup who want uncompromising sound characteristics or who want to future-proof their system for stage tuning.

Why 3.5 inches – and who would benefit from it?

3.5 inches is not a standard diameter, but a deliberate premium choice. The larger cross-section offers:

• More sound: More voluminous, clearer, with more bass punch. This system is uncompromisingly loud – truly furious in Sport mode, yet still discreet in Cruise mode thanks to the factory-installed valve control.
• Maximum throughput: Especially important for performance-enhanced S55 setups (Stage 2 / Stage 3). With software tuning, a larger downpipe, or methanol injection, the standard 3-inch system will eventually become a bottleneck – the 3.5-inch system will not.
• No OPF in the way: Without the factory-installed particulate filter, the exhaust gas flows through the system unobstructed. The result: an even clearer sound and even less back pressure.

Equal Length or Standard Piping

As with the 3-inch version, you also have a choice of piping here:

• Standard piping: Asymmetrical pipe routing, direct and compact design
• Equal Length Piping: Both banks are guided by pipes of exactly the same length – for more homogeneous exhaust gas pulsation, a more harmonious sound signature and more even flow behavior.

Especially in combination with 3.5 inches and non-OPF, Equal Length is the top class for S55-tuners who place maximum value on sound characteristics and consistency.

Flap control – factory-installed

The MThe F82/F83 has its own exhaust flap control system from the factory – the GRAIL system takes over this completely. Plug-and-play, no wiring, no remote control in the interior.

• In the M-Sport mode opens the flaps fully – full, brutal GRAIL sound
• In Comfort mode they remain closed – the system complies with ECE standards.

Configuration in the configurator

Before ordering, you select the following factors:

• Piping: Standard or Equal Length
• Tailpipe color: brushed stainless steel or black

Unsure about the configuration or non-OPF status of your M4? Send us the VIN via WhatsApp or contact form – we'll check it for you.

Tailpipes – 4x 100 mm round

The system comes with the classic M-4-pipe look: four round 100 mm tailpipes. This keeps the appearance close to the OEM look.M-Look of the F82 / F83 and harmonizes perfectly with factory or aftermarket diffuser.

• Brushed stainless steel: Sporty and elegant, high-quality look at the rear
• Black: A subtle yet aggressive look – goes well with the black package and dark rims.

Material & workmanship

LMade entirely of 304 stainless steel, with CNC-precision machined components. The silencers were specially developed in the GRAIL sound lab for the 3.5-inch non-OPF variant – focusing on maximum sound without compromising tone. Flow-optimized pipe routing minimizes exhaust backpressure, and the solid stainless steel valves switch precisely and reliably for everyday use.

Highlights

• Specifically designed for BMW M4 F82 / F83 without OPF
• 3.5 inches – maximum throughput for non-OPF and stage setups
• ECE type approval – registration-free despite uncompromising volume
• Choice between standard or equal length piping
• L304 stainless steel, handcrafted in Germany

Order with installation from FLOW DOWN®

FLOW DOWN® is an official GRAIL partner in the Ruhr area. When you order with installation, you'll receive our fair deposit payment model:

• 50% deposit upon order placement – we will then order the system from GRAIL
• As soon as the system arrives at our workshop, we will arrange an installation date with you.
• You only pay the remaining amount after the installation has been completed – not before.

Important: The deposit payment option applies exclusively to bookings including installation and is only available via prepayment/bank transfer. PayPal or other payment methods are not accepted for this service.

Swiss suitability assessment

Upon request, you can receive a Swiss suitability assessment for the GRAIL system for an additional fee. If interested, simply contact support.

Suitable vehicles

• BMW M4 F82 Coupé without OPF
• BMW M4 F83 Cabrio without OPF
• BMW M4 Competition F82 / F83 without OPF

Note: This 3.5-inch system is exclusively for M4 models designed without a gasoline particulate filter. For MFor 4 with OPF, the shop offers a dedicated GRAIL exhaust system in 3 inches (with and without OPF versions). Not suitable for: M3 F80 (own system), M3 G80 / M4 G82 / G83 (S58, own facilities).

scope of delivery

• GRAIL 3.5 inch flap exhaust system suitable for BMW M4 F82 / F83 without OPF (in your chosen variant)
• 4x 100 mm round tailpipes in brushed stainless steel or black (depending on selection)
• mounting material
• ECE type approval as proof for the vehicle

Information on admission

Registration-free thanks to ECE type approval – despite its uncompromising volume, the system is fully legal within the EU with standard approval. For imported vehicles with different operating permits, please check registration requirements before ordering.

All brands, model names and manufacturers mentioned in this shop such as AUDI, BMW, Hyundai, Kia, Toyota, VW, Tesla are used solely to describe the compatibility of our products . They have no connection with the respective brand owners and, unless expressly stated, they are not original parts from these manufacturers.

FLOW DOWN® is an independent supplier of tuning and accessories. The use of the brand names mentioned is for guidance only and does not constitute a collaboration, licensing or approval by the respective rights holders . All trademark and name rights are held by their respective owners.