CARMODFINDERFind my car
HomeGarageBuildLegalityArticlesBrowsePlateContactFind my car

Is a Resonator Delete Legal in the UK?

Conditional

Deleting a resonator is legal in the UK only if the car keeps its main silencer and catalytic converter and does not end up louder than its type-approved level. It often adds drone, and if that tips it over the noise line it is no longer legal.

Why?

A resonator is a secondary chamber that cancels specific frequencies; it is not the main silencer and not an emissions part. Removing it is not automatically illegal the way deleting the silencer or the cat is, which is why it sits in conditional territory rather than a flat no.

The test is still noise. Regulation 54 requires the exhaust not to be altered to raise noise beyond the type-approved level, and the MOT nuisance check fails a car that is clearly louder than standard. A resonator delete on a quiet car might stay under the line; on a car that was already close, the extra drone can push it over.

So treat it as "legal if it stays quiet enough". Keep the main silencer and cat, and be honest about whether the car has become noticeably louder - because that is exactly what an examiner or officer is judging.

What decides if it's legal

  • The main exhaust silencer and catalytic converter must stay fitted.
  • The car must not end up louder than its type-approved level.
  • It must still pass the MOT nuisance (noise) check.
  • Excessive drone or volume after the delete makes it an offence.

Does it depend on your car?

Whether a delete stays under the noise line depends on how loud the specific exhaust already is, which varies by car. The rule it is measured against is the same for all.

Related legality guides

Find your car in the garage

Sources

This page is general guidance, not legal advice, on the rules in the UK for resonator delete. The detail varies by exact vehicle and changes over time - confirm with your insurer and the latest DVSA and GOV.UK guidance before modifying.