BMW F8X M3/M4 Valved Cat-Back Exhaust System

Equal-Length 2.75" Mid-Section with H-Pipe and 3.5" Axle-Back

(T304 Stainless Steel or Grade 5 Titanium)

Overview

The S55 engine powering the BMW F8X M3 and M4 is a performance masterpiece, but its stock exhaust note has long been criticized for excessive rasp and a lack of tonal depth. The Valvetronic Designs Equal Length Valved Sport Exhaust System is a direct-fit cat-back exhaust for the 2015–2020 BMW F80 M3 and F82/F83 M4 that eliminates S55 exhaust rasp, lets you switch between quiet and aggressive valve modes on demand, and reduces weight by up to 49.2 lbs compared to the OEM exhaust (saving 21.7 lbs in T304 stainless steel or 49.2 lbs in Grade 5 titanium).

This system features a 2.75-inch equal-length mid-section with an H-pipe feeding into a 3.5-inch axle-back. The equal-length design smooths the exhaust tone across the rev range while preserving the aggressive character owners love. With valves open, gases exit freely from the passenger-side tips for maximum volume and performance. With valves closed, flow is routed through our quad-chamber muffler to the driver-side tips for a quieter, more refined note—ideal for daily driving.

No cutting or welding is required—this is a true direct bolt-on system designed to mount to factory points.

Why It Works

Equal-Length Mid-Section: Balances pulses for a cleaner, smoother tone without losing aggression.
H-Pipe Design: Improves scavenging for a fuller, more refined sound.
Dual-Mode Operation: Raw and loud (open) or subdued and civilized (closed).

Sound & Control

Valves Open: Aggressive, free-breathing tone with reduced rasp and improved high-rpm clarity.
Valves Closed: Stock-like sound levels for stealthy driving.
Electronic Valve Control: Includes standalone controller; OEM integration available.

Construction & Options

Materials: T304 stainless steel or Grade 5 titanium.
Weight Savings: –21.7 lb (Stainless) / –49.2 lb (Titanium) vs. OEM.
Craftsmanship: Precision TIG welds and fully mandrel-bent tubing for maximum flow.
Tips: Multiple premium finish options to complement your M3 or M4.

Fitment

2015–2018 BMW M3 (F80)
2015–2020 BMW M4 Coupe (F82)
2015–2020 BMW M4 Convertible (F83)

Installation Notes

Direct bolt-on; no cutting or welding required.
100% reversible—return to stock at any time.
Note for S55 Owners: On free-flow/race downpipes, “2k rpm rasp” may be present during low-rpm shifts. For the most refined tone, we recommend high-flow (200 cell) catalytic converters.