Remus GPF Cat-Back Exhaust for Audi S3 GY | 4x 102mm GT Titanium

The REMUS GPF-back system for the Audi S3 8Y/GY is essentially an upgraded exhaust path after the gasoline particulate filter (GPF). That is important because it changes the exhaust character and flow without removing the GPF itself.

REMUS lists the 8Y S3 system with 76 mm tubing versus the original 70 mm, with a resonated front section, sport rear silencer, quad outlet tubes and selectable 102-mm tailpipes. 

What the system actually does

OEM S3:

2.0 TFSI → Turbo → GPF → OEM exhaust → mufflers → 4 outlets

REMUS GPF-back:

2.0 TFSI → Turbo → GPF → 76-mm REMUS section → resonator → sport silencer → 4 × 102-mm tips

The GPF remains upstream, so this isn’t the same as deleting the emissions equipment.

Why the 76-mm pipe matters

The diameter increases from approximately 70 → 76 mm. That gives roughly 18% greater cross-sectional area:

A = D^2 

(76/70)^2 ~1.18

So the exhaust has substantially more flow area, although 18% more area does not mean 18% more horsepower. 

The actual power effect depends on the turbo, GPF restriction, muffler design, ECU calibration and operating point.

REMUS describes the system as offering improved performance/torque, sporty sound and weight optimisation. 

The interesting part: 4 × 102-mm GT Titanium

The GT Titanium tips are primarily the visual and thermal character of the system. The large 102-mm outlets give the S3’s rear a much more aggressive appearance, while the titanium finish provides the motorsport-style appearance.

The REMUS catalogue also offers 102-mm carbon/titanium-internal versions, while the conventional 102-mm options include angled and straight-cut configurations. 

GPF-back vs cat-back

Technically, GPF-back is the more precise description for this S3 application.

It means the GPF remains untouched:

Turbo → GPF → REMUS exhaust

That’s different from a traditional “cat-back” system where the catalytic converter remains but the terminology refers to everything downstream of the catalytic converter.

Resonated vs racing configuration

For a road-oriented S3, the resonated, EEC/ECE-approved configuration is particularly significant. REMUS offers a resonated GPF-back system for the 8Y with approval and states that installation uses the original mounting points without vehicle modifications. 

There is also a RACING configuration. REMUS explicitly states that the Racing GPF-back version has no EEC approval, so it is intended differently from the approved road configuration. 

Engineering view

The key isn’t simply “bigger pipe = more power.”

The real engineering objective is:

Turbo outlet → GPF → pressure management → pipe velocity → resonator → muffler absorption → outlet

A good exhaust must reduce unwanted back-pressure without destroying exhaust-gas velocity, acoustic control or low-speed drivability.

For the S3’s 2.0 TFSI, the REMUS system therefore makes most sense as a supporting modification to an otherwise staged build rather than expecting the exhaust alone to transform the engine.

In one sentence:
The REMUS system turns the S3 8Y’s post-GPF exhaust from a relatively restrictive OEM acoustic/flow system into a larger 76-mm, resonated performance exhaust with four 102-mm GT-style outlets, while retaining the GPF in the approved configuration. 

Remus GPF Cat-Back Exhaust for Audi S3 GY | 4x 102mm GT Titanium