Valvetronic Designs T304 Stainless Valved Axle-Back Exhaust - 2020+ BMW M3 & M4 (G80/G82/G83)

This Valvetronic Designs system is a 2.75" T304 stainless valved axle-back for the BMW G8X M3 and M4 — the rear section only, not a full exhaust system. It bolts on independently of the midpipe and pairs a quad-chamber muffler with electronic valves and an included controller, giving you a level of valve control the factory setup doesn't offer.

Here's why that controller matters: on the factory G8X exhaust, the valves only sit fully open at idle. Even in Sport mode with the exhaust button toggled, once the car is rolling the factory flaps modulate based on throttle input and the car goes quiet again. Valvetronic Designs' included controller removes that behavior, so you decide when the valves stay open, not the car's throttle-position logic.

Important Compatibility Information

This is the axle-back section only. It replaces the rear section of your exhaust and does not include or replace the midpipe. If you're also upgrading the midpipe, note that Valvetronic Designs' V1 and V2 midpipe components are not compatible with V3.

BMP also carries this axle-back in Grade 5 titanium for this same platform.

Why Upgrade

The factory G8X exhaust valves are only 100% open at idle. Even with Sport mode and the exhaust button both engaged, the flaps close back down under throttle once you're moving, so the car goes quiet exactly when you'd want it loud. This axle-back's included controller takes that decision away from the car's throttle-position logic and puts it in your hands, on top of a quad-chamber muffler and a full stainless rear section that replaces the restrictive factory unit.

Features

• 2.75" T304 stainless steel, axle-back section
• Quad-chamber muffler design
• Fully mandrel-bent tubing, precision TIG welds
• Electronic valves with included controller, removing the factory's throttle-based valve behavior
• OEM valve integration also available for drivers who prefer factory-style control
• Premium tips included
• Can be installed independently of the midpipe
• 100% reversible to factory

What's Included

• 2.75" T304 stainless valved axle-back exhaust with quad-chamber muffler
• Electronic valve controller
• Premium exhaust tips
• All necessary clamps and hardware

Not included: the midpipe. This axle-back does not replace or come with a Valvetronic Designs midpipe, and BMP does not stock one for this platform. This system also bolts to your OEM or an aftermarket downpipe, which is not included.

Installation Notes

The axle-back can be installed on its own, without replacing the midpipe. When installing only the axle-back, the rear-section cut on the OEM pipe is made at the second dimple, per Valvetronic Designs' published install guidance. BMP also stocks a G8X M3/M4 extended chassis brace as a separate part; it is not required for or included with this axle-back.

Ownership Notes

If a valve actuator or harness ever needs replacing, BMP stocks the Valvetronic Designs electronic valve harness kit sized for this axle-back's two-actuator setup.

Product Specifications

• Fitment: for the G80 M3 and G82/G83 M4
• Scope: axle-back (rear section) only
• Material: T304 stainless steel
• Diameter: 2.75", axle-back section
• Design: quad-chamber muffler
• Valve control: electronic valves with included controller; OEM valve integration also available
• Compatibility note: V1 and V2 components are not compatible with V3

Need a Valvetronic Designs System for a Different BMW M?

• G87 M2 axle-back
• G20 M340i & M440i valved sport exhaust

Frequently Asked Questions

Is this a full exhaust system?
No. This is the axle-back section only — the rear part of the exhaust. It does not include or replace the midpipe.

Why do I need a controller if my G8X already has valves?
The factory valves only sit fully open at idle. Once the car is moving, the factory flaps modulate on throttle input even in Sport mode with the exhaust button on, so the car quiets back down. This axle-back's included controller lets you keep the valves open on your own terms instead.

Can I install this without also replacing the midpipe?
Yes. Valvetronic Designs publishes that the axle-back can be installed independently. Installing it alone requires cutting the OEM rear section at the second dimple.

Do I need the extended chassis brace to install this?
No. The chassis brace is a separate part BMP stocks; it is not required for or included with this axle-back.

Is this compatible with an older Valvetronic Designs G8X system I already have?
Check your generation first. Valvetronic Designs states V1 and V2 midpipe components are not compatible with V3. contact your BMP Tuning rep if you're unsure which generation you have.

Is titanium available for this platform?
Yes, BMP carries a titanium version of this same axle-back separately.