BMW G8X (G80 M3 / G82 M4) Downpipe & Catback Fitment Guide

Does This Fit My Car? G8X Exhaust Fitment Breakdown

If you're building a BMW G80 M3, G82 M4, or G83 M4 Convertible, exhaust is one of the highest-impact upgrades you can make — both for sound and performance. This guide covers exactly which IRL downpipes and catback systems fit your chassis, what the differences are between catted and catless, and how to configure your order.

Chassis & Engine Compatibility

All IRL G8X exhaust products are engineered for the S58 twin-turbo inline-six found in:

• G80 M3 (sedan, 2021+) — Competition & base
• G82 M4 (coupe, 2021+) — Competition & base
• G83 M4 (convertible, 2021+) — Competition xDrive

All three share the same S58 engine and exhaust routing, so fitment is identical across the G80/G82/G83 lineup. xDrive and RWD variants use the same downpipe and midpipe connections.

Downpipe Options: Catted vs Catless

Choosing between catted and catless is the biggest decision you'll make on the downpipe. Here's the honest breakdown:

Catless (off road use )

The IRL G8X MaxFlow Race Downpipes remove the catalytic converter entirely. This delivers the maximum flow and sound, but will trigger a check engine light (CEL) without an appropriate tune. These are designed for track and race use.

• IRL G8X MaxFlow Race 400-CEL Downpipes — Our #1 seller. Includes bung for wideband O2. Best for tuned builds.
• IRL G8X 3.5" MaxFlow Race Downpipes — Larger 3.5" diameter for maximum flow on aggressive tunes.
• IRL G8X MaxFlow Race 200-CEL Downpipes — Mid-spec catless option.

Catted (off road use )

For daily drivers or emissions-tested vehicles, the IRL G8X EPA Compliant 400 Cell Catted Downpipes use a high-flow 400-cell metallic cat. You get a meaningful sound and flow upgrade over stock without triggering a CEL on an OTS (off-the-shelf) tune.

• No CEL on stock or light tunes
• Street legal in most states (check your local emissions rules)
• Recommended if you daily your M3/M4 or live in a strict emissions state

Catback Systems

Our best-selling catback for the G8X platform is the IRL G80 G82 G83 Full Modular Catback. "Modular" means you can run it in multiple configurations:

• Full catback — Midpipe + axleback for the complete IRL exhaust note
• Midpipe only — Pair with your existing axleback or OEM tips
• Axleback only — Drop-in upgrade for a sound change without touching the midpipe

For a valved exhaust with mode-switchable volume, see the IRL V2 G80 G82 G83 Catback Valved Exhaust, which integrates with our V2 Valve Controller for app-controlled or switch-controlled sound modes.

Recommended Combinations

Installation Notes

• All IRL G8X downpipes are direct bolt-on — no cutting or welding required
• Estimated install time: 2–3 hours with a lift or ramps
• Downpipe install requires removal of the undertray and heat shield
• We recommend a tune after any catless downpipe install to address the CEL and optimize fueling
• All hardware and gaskets are included

Shop G8X Exhaust

Browse the full lineup for your platform:

• G80 / G82 / G83 M3 Collection
• IRL G80 G82 G83 Full Modular Catback
• IRL G8X MaxFlow Race 400-CEL Downpipes
• IRL G8X EPA Compliant 400 Cell Catted Downpipes

Questions about fitment? Drop us a message — we're happy to help you configure the right setup for your build.