Is a cat-back exhaust legal in Ireland? What the NCT checks.

Updated 30 October 2026.

A cat-back exhaust replaces only the part of the system behind the catalytic converter: your factory catalytic converter, oxygen sensors and on-board diagnostics stay exactly as they are, and with a Rog valved system, valves closed, your car sounds very close to stock, day to day and at the NCT. Valves open, it has the voice you chose for it. If you replace the front section too, our 200-cell sports catalytic converter keeps emissions control. Each system is built from your VIN, from a 3D scan of the chassis and of the original system, and bolts onto the original mounting points with no welding. Free technical documentation for your paperwork, a 3-year warranty and free delivery.

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Contents 6

1. At the NCT: how it works.
2. The rules, in short.
3. Find the exhaust for your car.
4. Frequently asked questions.
5. Write to us.
6. Sources.

At the NCT: how it works.

• Noise is assessed subjectively: a sound level meter is only used if the tester considers the noise may be borderline, with the car stationary (S.I. No. 415/2017, Schedule 3, item 8.1.1). Valves closed, your car goes in sounding very close to stock.
• A clear figure: if the tester does measure, the fail level is 99 dB.
• The silencer itself: the tester checks that the noise suppression system is secure, undamaged and correctly fitted. A Rog system bolts onto the original mounting points, with no welding.
• Emissions equipment (item 8.2.1.1): the emission control system fitted by the manufacturer must be present, unmodified and working. A cat-back leaves it untouched.
• Your papers: you bring your vehicle registration certificate, and the VIN on it is checked against the car. That VIN is all we need to build your system.
• How often: a car is first tested from the fourth anniversary of its first registration, then every two years until its tenth anniversary, then every year until its thirtieth, and every two years after that. A car brought into Ireland is due its first test on arrival if it is four years old or more (regulation 3).

The rules, in short.

Rog exhausts carry no type approval: that is a choice, because a system with type approval sounds almost like the original one, and the valves give you both. The Road Traffic (Construction, Equipment and Use of Vehicles) Regulations 1963 ask for a silencer that reduces exhaust noise to a reasonable level (article 29), kept in good working order and not altered so as to make the noise greater (article 34); UN Regulation No. 59, the international standard for replacement silencers, asks a system with several modes to meet its requirements in each of them. The NCT schedule also refers to a modifications report "where required" (item 0.3): ask your NCT centre whether your configuration needs one, with our free technical documentation to hand. For a front section, as for the noise, it is the NCT tester who decides.

On the road, article 85 of the 1963 regulations asks drivers not to cause avoidable excessive noise: valves closed in town and at night, your car stays very close to stock, and you open them when you choose. To see where noise cameras are already in use in Europe, see our table of noise cameras in Europe.

Find the exhaust for your car.

Each product page shows the system, its options and its sound; each guide explains the configuration in detail. A few examples:

• Volkswagen Golf 7 R / 7.5 R: the exhaust and the guide.
• Volkswagen Golf 8 R: the exhaust and the guide.
• BMW M3 / M4 F80 / F82 / F83: the exhaust and the guide.
• BMW M3 / M4 G80 / G81 / G82 / G83: the exhaust and the guide.
• BMW M2 G87: the exhaust and the guide.

Your car is not on the list? All our exhausts, by brand.

Frequently asked questions.

Is a cat-back exhaust legal in Ireland?
A cat-back does not touch your factory catalytic converter, oxygen sensors or on-board diagnostics, and, valves closed, a Rog system sounds very close to stock. At the NCT, noise is assessed subjectively, a meter is only used if it may be borderline, and the NCT tester decides.

What is the NCT noise limit?
If the tester measures your car while stationary, the fail level is 99 dB. Valves closed, a Rog system stays very close to stock; the NCT tester decides.

Will the system fit my car?
Yes: it is built from your VIN, from a 3D scan of the chassis and of the original system, and checked before production. It bolts onto the original mounting points with no welding, at the garage of your choice.

What happens to my catalytic converter?
With a cat-back, it stays in place, with its sensors. If you also replace the front section, the 200-cell sports catalytic converter keeps emissions control; the catless version is for track use only. At the NCT, the tester decides.

Do I need to tell my insurer?
Under the Consumer Insurance Contracts Act 2019, you answer the specific questions your insurer asks, honestly and with reasonable care. Tell your insurer about the new exhaust as your policy requires: our free technical documentation makes it easy.

Does Rog provide documents?
Yes: on request, we send you the technical documentation for your system free of charge, describing your configuration, for the NCT or for your insurer. At the NCT, the tester decides.

Write to us.

Email us at contact@rogmotorsport.com: we reply in writing, in English, within 24 hours. For instant answers: the Rog Advisor and our FAQ.

As set out in our terms and conditions of sale, it is up to each buyer to check the rules in their country.

Sources.

1. S.I. No. 415/2017, Road Traffic (National Car Test) Regulations 2017 (regulations 3 and 5; Schedule 3, items 0.3, 8.1.1 and 8.2.1.1), as made, accessed 30 October 2026: https://www.irishstatutebook.ie/eli/2017/si/415/made/en/print
2. S.I. No. 190/1963, Road Traffic (Construction, Equipment and Use of Vehicles) Regulations 1963, as made, articles 29, 34 and 85, accessed 30 October 2026: https://www.irishstatutebook.ie/eli/1963/si/190/made/en/print
3. Consumer Insurance Contracts Act 2019, section 8, accessed 30 October 2026: https://www.irishstatutebook.ie/eli/2019/act/53/enacted/en/print
4. NCTS, National Car Testing Service, accessed 30 October 2026: https://www.ncts.ie/
5. Road Safety Authority, accessed 30 October 2026: https://www.rsa.ie/
6. UN Regulation No. 59, replacement silencing systems (Official Journal of the EU, L 2025/844), point 6.1.3.2, accessed 29 October 2026: https://data.europa.eu/eli/reg/2025/844/oj

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