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$3,499.00 USD
Sale price
$2,999.00 USD
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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 Cat-Back is the definitive solution—eliminating the factory harshness and unlocking the rich, balanced sound the S55 was always capable of producing.
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.
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.
What’s Included
2.75" equal-length H-pipe mid-section
3.5" axle-back with quad-chamber muffler
Electronic valve system with controller (OEM integration optional)
All necessary clamps and hardware
Specifications
Mid-Section Diameter: 2.75" equal-length with H-pipe
Axle-Back Diameter: 3.5"
Material: T304 stainless steel or Grade 5 titanium
