BMW Z4 M40i (B58) Performance Exhaust System — 3.5” Midpipe + Dual 2.75” Quad-Tip Design

The BMW Z4 M40i delivers one of the most rewarding B58 driving experiences, but its factory exhaust setup leaves a lot of performance and emotion on the table. The stock system relies on a narrow mid-section and restrictive merging points, bottlenecking exhaust flow and muting the signature B58 tone that enthusiasts crave. Our redesigned system unleashes the engine’s true character with a dramatic increase in flow, a deeper and more aggressive sound profile, and improved responsiveness—especially for tuned vehicles or cars running upgraded downpipes.

At the core of this system is a full 3.5-inch high-flow midpipe, engineered to eliminate factory choke points and significantly reduce backpressure. This oversized midpipe transitions into dual 2.75-inch pipes through a precision casting Y-collector, ensuring perfectly smooth exhaust gas distribution without turbulence. The result is a cleaner, more unified exhaust note with enhanced turbo spool and sharper throttle response across the entire RPM range.

To complete the transformation, we developed a true quad-tip rear section, replacing the factory’s faux-quad appearance with an actual dual-branch layout. This not only sharpens the Z4’s rear aesthetics but also improves acoustic separation between the exhaust banks, giving the B58 a more exotic, performance-oriented tone. The system integrates seamlessly with the OEM valve control for daily comfort yet becomes noticeably more aggressive and expressive when opened.

Built for performance today and headroom for future mods, this exhaust is ideal for owners planning ECU tunes, high-flow downpipes, or upgraded turbos—ensuring maximum efficiency without introducing drone or unwanted harshness.

Key Specifications

Fitment

• BMW Z4 M40i (G29) — 2019–Present

• B58 3.0L Turbocharged Inline-6 Engine

Configuration

• 3.5” single midpipe → precision-cast Y-collector → dual 2.75” rear section

• True quad-exit design

Materials

• AISI 304 Stainless Steel (standard)

• 6AL-4V Aerospace-Grade Titanium (optional; 55–60% lighter, more exotic tone)

Manufacturing

• CAD-modeled & 3D scanned

• Mandrel-bent tubing

• Precision casting collector

• Hand TIG-welded construction

Tip Options

• Real quad 4” tips

• Finishes: Chrome / Burnt / Satin Black / Forged Carbon Fiber

Valve Control

• Full OEM valve compatibility

• Optional remote-control valve module included

Installation

• Direct bolt-on

• No cutting

• Factory valve motor transfers over