Akrapovic Slip-On Line Titanium Axle-Back Exhaust (Rear Muffler/Back Box/Backbox) for BMW G80 M3/G82 M4 2021+ incl. Competition & xDrive, OPF/GPF Compatible, ECE Approved, Carbon Tip Options – Performance Sports Silencer – S-BM/T/21H

Elevate your G80 or G82 with a premium titanium axle-back that pairs motorsport craftsmanship with everyday usability. This lightweight rear section is OPF GPF friendly, EU road legal when used as supplied, and finished with stunning carbon-fibre outlets for a true performance look. Part number S-BM/T/21H.

Why this titanium rear section is the upgrade enthusiasts choose

• Serious weight saving for sharper response, with 8.3 kg trimmed over the factory back box.
• Real-world gains proven on the dyno. Uplift of +8.0 kW at 6,000 rpm and +13.9 Nm at 5,000 rpm on a comparable M4 Competition.
• Valved sound control included. Refined on cruise, deeper and more aggressive under load.
• Tailpipe choices to suit your style. Go bold with octagonal titanium bodies with carbon sleeves, or choose a classic cylindrical option.
• No coding or remap required. Plug-in installation for both filtered and non-filtered cars.
• Optimised flow from precision cast twin collectors produced in-house for a smooth, clean exit.
• ECE approved for vehicles equipped with OPF GPF when installed as a Slip-On only.

Key numbers

• Power increase: +8.0 kW at 6,000 rpm
• Torque increase: +13.9 Nm at 5,000 rpm
• Mass reduction: 8.3 kg versus stock
• Material: high-grade titanium with carbon-fibre tailpipe finish
• Configuration: axle-back Slip-On, OPF GPF compatible
• Works with xDrive variants
• Part number: S-BM/T/21H

Vehicle fitment

• BMW G80 M3 2021+
• BMW G80 M3 Competition 2021+
• BMW G82 M4 2021+
• BMW G82 M4 Competition 2021+
• Includes xDrive models

Mandatory tailpipe selection

A Tail Pipe Set in carbon is required and purchased separately. Choose the striking octagonal design with carbon sleeve or the timeless cylindrical style to complete your titanium axle-back.

Optional add-ons for track and closed-circuit use

• OPF delete Evolution titanium link pipe set
• Catless downpipe
• High-flow catalytic downpipe
• Rear carbon-fibre diffuser in high gloss
• Sound Kit

Important note. If optional link pipes, downpipes or the Sound Kit are installed, ECE approval of the Slip-On Line Titanium is no longer valid.

Road legality

• ECE type approved when used as a Slip-On on vehicles equipped with OPF GPF.
• Suitable for OPF and non-OPF cars. No ECU recalibration required for this configuration.

Installation and support

Professional fitting available at MJ Modifications in Warwickshire. Request a quote via info@mjmodifications.co.uk. We have fitted and used this system extensively and customer feedback on tone, quality and drivability has been consistently excellent.

Manufacturer and warranty

• Manufacturer: Akrapovic
• Warranty: Akrapovic One Year Warranty
• Part number: S-BM/T/21H

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