FORGE MOTORSPORT Audi RS3 8Y Sportback Milltek Exhaust FMSSXAU975

 

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FORGE MOTORSPORT

Audi RS3 8Y Sportback Milltek Exhaust FMSSXAU975

The Milltek Sport Exhaust FMSSXAU975, sold through Forge Motorsport, is a premium OPF/GPF-back Race Non-Resonated exhaust system engineered specifically for the Audi RS3 8Y Sportback (2021–2024) equipped with the legendary 2.5L EA855 EVO turbocharged inline-five engine. 

It replaces the factory exhaust from the gasoline particulate filter (OPF/GPF) rearward while retaining emissions equipment. 

Technical Specifications

• Vehicle: Audi RS3 8Y Sportback (2021–2024)
• Engine: 2.5 TFSI EA855 EVO
• Exhaust Type: OPF/GPF-back
• Configuration: Race Non-Resonated (loudest version)
• Pipe Diameter: 80 mm (3.15 inches)
• Material: T304L aircraft-grade stainless steel
• Manufactured: United Kingdom
• Warranty: Lifetime warranty for the original purchaser (excluding catalytic converters and flex sections). 

Technical Analysis

1. Maximized Exhaust Gas Flow

The large 80 mm mandrel-bent tubing minimizes exhaust backpressure compared with the restrictive factory system.

Benefits include:

• Improved turbocharger efficiency
• Faster turbine acceleration
• Better high-RPM breathing
• More consistent power during repeated acceleration

Although peak horsepower gains on a stock RS3 are modest, the exhaust becomes increasingly beneficial on Stage 1 and Stage 2 tuned vehicles.

2. Authentic Five-Cylinder Sound

The EA855 engine’s 1-2-4-5-3 firing order produces one of the most distinctive exhaust notes available.

This non-resonated system enhances:

• Deep idle tone
• Aggressive mid-range growl
• Iconic Audi five-cylinder warble
• Sharp overrun crackles (where supported by ECU calibration)

Unlike many systems that simply increase volume, Milltek focuses on preserving sound quality.

3. Reduced Restriction

Compared with OEM:

• Larger pipe diameter
• Freer-flowing silencers
• Reduced turbulence
• Less pumping loss

This improves:

• Engine responsiveness
• Turbo spool characteristics
• High-speed acceleration

4. Premium Construction

Milltek’s use of T304L stainless steel provides:

• Excellent corrosion resistance
• Superior weld durability
• Long-term structural integrity
• Resistance to heat cycling

The material also resists discoloration better than lower-grade stainless steel. 

Advantages

Excellent sound engineering

Produces an aggressive yet refined five-cylinder soundtrack without sounding excessively harsh.

Improved throttle response

Reduced exhaust restriction allows the turbo to react more quickly during transient throttle inputs.

High-quality fitment

Milltek systems are widely recognized for OEM-like fitment with accurate hanger placement and minimal installation issues.

Track-capable airflow

The 80 mm design supports significantly higher power levels than stock, making it suitable for future tuning.

Premium materials

Full T304L stainless construction ensures long service life.

Disadvantages

Expensive

This is among the higher-priced stainless steel exhaust options.

Non-resonated design

Cabin drone may be noticeable between approximately 2,000–3,000 rpm depending on driving conditions and transmission gear. Community feedback generally describes it as louder with some drone but still more refined than many track-focused systems. 

Limited gains on a stock vehicle

Without ECU tuning or additional airflow upgrades, most benefits are in sound and responsiveness rather than large horsepower increases.

Comparison Against Competitors

Brand	Sound	Drone	Performance	Weight	Character
Milltek Race Non-Res	5	Medium	4	4	Balanced performance and refinement
Akrapovic Titanium	5	Very Low	5	5	Ultimate premium option with significant weight savings
AWE Track	5	High	4	3	Extremely loud and aggressive
Armytrix Valved	5	Adjustable	4	4	Versatile due to valve control
Remus	4	Low	4	4	Refined European character

Ideal Supporting Modifications

For the best overall package on an Audi RS3 8Y:

• Forge Carbon Fibre Induction Kit
• Forge Intercooler
• Forge Turbo Inlet Pipe
• Stage 1 or Stage 2 ECU calibration
• High-flow intake piping

Together, these modifications improve airflow from intake to exhaust, allowing the EA855 engine to realize greater performance potential. 

Verdict 

The Forge Motorsport / Milltek FMSSXAU975 is one of the strongest stainless-steel exhaust upgrades available for the Audi RS3 8Y Sportback. 

It delivers a meaningful improvement in exhaust flow, a richer and more authentic five-cylinder soundtrack, and OEM-quality construction without sacrificing everyday usability.

Overall ratings:

• Performance: 9.3/10
• Sound Quality: 10/10
• Build Quality: 9.8/10
• Daily Comfort: 8.5/10
• Track Suitability: 9.5/10
• Value for Money: 8.8/10

Overall Score: 9.4/10

This exhaust is particularly well suited for enthusiasts who want a premium, durable system that complements the RS3’s distinctive five-cylinder character while leaving room for future performance upgrades.

FORGE MOTORSPORT

Audi RS3 8Y Sportback Milltek Exhaust FMSSXAU975