Exhaust system and stage 1: should you change the exhaust?

Updated: 30 September 2026.

No: stage 1 is by definition a remap with no parts changed, and it works with the original exhaust. Changing the exhaust system as well mainly brings sound, less weight and the choice of opening it up or not; it is the downpipe, not the exhaust system, that takes you to stage 2 and unlocks most of the extra horsepower.

Here are the real gaps between stage 1 alone, stage 1 with an exhaust system and stage 2, with figures for three common turbocharged engines, followed by what to set up on the mapping and valve side.

Stage 1, stage 2: the definitions.

The terms are not standardised, but most tuners agree. BR-Performance, a French remapping network, defines them as follows:

• Stage 1: “a custom remap on a dyno, without changing any mechanical parts”.
• Stage 2: “mapping plus parts around the engine (exhaust, intake)”. On a turbocharged engine, the exhaust part in question is the downpipe, with a sports catalytic converter.
• Stage 3: internal engine parts or a bigger turbo.

Stage 1 therefore stays within the margins designed in by the manufacturer, with the original exhaust. The question is not “do I have to” but “what do I gain”.

Stage 1 without an exhaust, with an exhaust, with a downpipe: the real gaps.

Figures published by BR-Performance for three turbocharged engines, checked on 30/09/2026:

What this table shows:

1. Stage 1 delivers most of the gain: + 60 to + 70 hp for a few hundred euros.
2. Stage 2 adds roughly another 20 hp, but requires parts, including the downpipe with a sports catalytic converter (list published for the Golf 7.5 GTI: exhaust with sports catalytic converter, airbox, inlet pipe).
3. A cat-back exhaust system alone does not change the category: stage 1 with an exhaust system is still stage 1. On a modern turbocharged engine, the original silencer is not the main restriction; the measurable power gain from a cat-back is small.

What an exhaust system really adds at stage 1.

If not power, why change it? For four concrete reasons:

• Sound. A stage 1 makes the car faster, not more expressive. Original silencers, especially with a petrol particulate filter, muffle exactly what the remap frees up. On our internal scale of intensity with the valves open, the original exhaust system scores 3 out of 10, our cat-back 7.
• Choice. With a valved exhaust system, you decide: closed, a sound close to the original for daily driving and vehicle inspection; open, the engine's full voice.
• Weight. A few kilos less at the rear, more in titanium (around 40% lighter than stainless steel for the same design).
• What comes next. If you move to stage 2 later, the exhaust system is already there: only the downpipe is left.

Mapping and valves: what to set up.

Three points to go over with your tuner:

1. The valves. On many cars, the factory valves are controlled by the ECU according to the drive mode. A Rog exhaust system can use this original control; it can also work with the Rog remote, which opens and closes them whatever the mode. If your remap changes the logic of the factory valves, let us know when you order.
2. “Pops and bangs”. The bangs on lift-off are a mapping option, not an effect of the exhaust system. A free-flowing exhaust system makes them more audible. Before asking for them, read pop and bang: how it works, is it risky?
3. Emissions control. A serious stage 1 respects emissions standards. If you move to stage 2 with a downpipe, choose a 200-cell sports catalytic converter: emissions control stays in place (see 200-cell sports catalytic converter).

In what order to do things.

The most disappointing case: fitting a downpipe without a remap and hoping for horsepower. On a recent engine, boost pressure is regulated; without new mapping, expect sound and responsiveness, not power (details in downpipe: what it is and what it does).

Rog exhaust systems for a remapped engine.

Our exhaust systems are valved cat-backs made to order from your VIN, in 304 stainless steel or titanium, with a brushed, chrome, gold or purple finish. Fitting requires no welding or cutting, and the downpipe can be chosen as an option to prepare for stage 2. Examples, starting prices in stainless steel checked on 30/09/2026: BMW M140i exhaust from €2,490, Volkswagen Golf 7.5 GTI exhaust from €2,490, Audi RS3 8Y exhaust from €3,390. Free shipping, 20 working days, 3-year warranty. To understand how exhaust gases and mapping interact: how exhaust gases influence engine mapping.

Frequently asked questions.

Do you need to change the exhaust to do a stage 1?
No. A stage 1 is a remap with no parts changed, designed for the original exhaust.

Does an exhaust system add horsepower at stage 1?
Not much on a modern turbocharged engine. The gain comes mainly from the remap; the exhaust system brings the sound, the weight saving and the choice offered by the valves.

Do you need a remap after fitting a cat-back exhaust system?
No, a cat-back touches neither the engine nor the ECU. A remap becomes useful if you also change the downpipe.

Stage 1 or exhaust system: which comes first?
If you want power, stage 1. If you want sound, the exhaust system. The two are independent and can be combined.

Does a valved exhaust system pass vehicle inspection with a stage 1?
Presented with the valves closed, the car stays close to its original sound, and the cat-back keeps the original emissions control. The inspection judges noise by ear and measures the gases.

Sources.

All consulted on 30/09/2026.

1. BR-Performance, stage definitions (in French): https://www.br-performance.fr/brp-paris/reprogrammation/stages/
2. BR-Performance, BMW M140i stage 1 and stage 2 (in French): https://www.br-performance.fr/brp-paris/reprogrammation/1-voitures/5-bmw/508-serie-1/7080-f2x-lci-2015-2019/8598-m140i/
3. BR-Performance, Volkswagen Golf VII Facelift GTI 2.0 TSI stage 1 and stage 2 (in French): https://www.br-performance.fr/brp-paris/reprogrammation/1-voitures/54-volkswagen/2968-golf/9023-vii-facelift-02-2017-2020/9027-gti-2-0-tsi/
4. BR-Performance, Audi RS3 8Y 2.5 TFSI stage 1 (in French): https://www.br-performance.fr/brp-paris/reprogrammation/1-voitures/11-audi/3782-rs3/11445-8y-10-2021/12859-rs3-2-5-tfsi-gpf/