Dinan Cat-Back Exhaust for BMW 3 Series F30 340i & 4 Series F32 440i B58 – 304 Stainless Performance/Sports System, Twin 89mm (3.5") Polished Tips, Helmholtz Drone-Reducing, Direct-Fit Catback Backbox/Muffler Rear Silencer Upgrade

Dinan Cat-Back Sports Exhaust for BMW F30 340i and F32 440i (B58) with Polished 89 mm Twin Tailpipes

Transform the character of your B58-powered 3 Series or 4 Series with a premium cat-back from Dinan. This stainless system releases a richer inline-six tone, sharper throttle feel and a more engaging drive, while keeping motorway cruising calm thanks to a resonance-tuned chamber that suppresses low‑rpm boom. It is the ideal upgrade if you want a tasteful sound increase without the tiring cabin hum.

Highlights

• Less restriction for crisper response and improved flow
• Refined on light throttle, purposeful under load with addictive burbles
• Resonance-tuned design to curb cabin drone at steady speeds
• Crafted from 100% 16 gauge 304 stainless steel for durability and corrosion resistance
• Twin 89 mm 3.5 inch polished tailpipes for an OEM-plus finish
• Direct bolt-on using factory mounting points for precise fitment

Why this system

Dinan engineers build systems that look factory, fit perfectly and sound spot on. The B58 in the 340i and 440i responds brilliantly to a freer flowing rear section, and this cat-back strikes the sweet spot between everyday refinement and weekend excitement. We have supplied and used this exhaust ourselves and customer feedback has been consistently positive on tone, build quality and fit.

Fitment

• BMW F30 340i 3 Series, B58 engine
• BMW F32 440i 4 Series, B58 engine

Sound and drivability

Expect a deeper, cleaner note with more presence on start-up and acceleration, without the boomy resonance that often spoils daily driving. Around town it stays civil; open it up and it delivers a sportier, more characterful soundtrack that suits the B58 perfectly.

Specification

• Material: 100% 16 gauge 304 stainless steel
• Tailpipes: Twin 89 mm 3.5 inch polished tips
• Configuration: Cat-back sports exhaust with tuned anti-drone chamber
• Mounting: Utilises OE hangers for a neat, secure install

Installation and fitting

Straightforward bolt-on replacement using the original mounting hardware. Prefer expert fitting? Book professional installation with MJ Modifications in Warwickshire. Request a quote: info@mjmodifications.co.uk.

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Upgrade your 340i or 440i with a high quality Dinan cat-back that looks right, sounds fantastic and is built to last.