BMW F80/F82/F83 M3/M4 Equal Length Valved Sport Exhaust System

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.
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.

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
Valves: Electronic, rapid open/close
Weight Savings: –21.7 lb (Stainless) / –49.2 lb (Titanium) vs. OEM
Design: Quad-chamber muffler for refined closed-valve tone

Shipping & Returns

Shipping on new purchases

In Stock Items:
In stock items typically ship within 1-3 business days. Most items arrive within 2 business days, but there are situations where it may take up to 5 business days.

Special Order Items:
Special order and out of stock items are product-specific and lead times can vary. Please e-mail us if you are looking for an ETA / Lead Time on a specific product. Special order orders are subject to cancellation if the vendor cannot provide any ETA.

Returns Policy

To start the return process, please e-mail sales@allianceracing.com

Include the following:
Subject "Return for Order#"
Order Number
Part Number
Reason

Returns are eligible for up to 14 days from delivery of items. Accepted refunds can take up to 7-10 business days to process. All refunds are subject to a 25% restocking fee, if opened. Customer may be responsible for return shipping. If 14 days have gone by since your item was delivered, unfortunately we can’t guarantee you a refund or exchange. We reserve the right to deny any return request, based on provided information.

Alliance Racing is not responsible for ensuring part fitment. It is the responsibility of the purchaser to ensure the parts being ordered are the correct fitment for the vehicle intended. Alliance Racing will not accept any returns for incorrect fitment after product is opened.

To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.

Shipping

To return your product, mail your product to:
Alliance Racing LLC
8810 Twin Lakes Blvd
Tampa, FL 33614

In many cases, you will be responsible for shipping costs to return your item. Shipping costs are non-refundable. If you receive a refund, the cost of shipping will be deducted from your refund.

Depending on your location, the time it may take for your exchanged product to reach you may vary.

If you are shipping an item over $100, you should consider using a trackable shipping service and/or purchasing Shipping Insurance.

Price Matching

To initiate a price match, please e-mail sales@allianceracing.com with the product information (SKU, URL, & Part Name) and a link to the competitors product page for us to validate the price match eligibility.

Please note that there are cases when we cannot offer a price match, but we will do everything in our power to try to match it. Some manufacturers have Pricing Policies that we have to adhere to.

Shop With Confidence

Competitive Pricing

Questions?

Free Shipping