Question to the Department for Transport:

To ask the Secretary of State for Transport, if she will consider expanding of the use of further equipment in MOT tests to accurately assess the noise level of motorcycles and their silencers.

Exhaust noise is currently tested subjectively during the MOT test. The tester must consider if exhaust noise from the vehicle is unreasonably above the noise level you’d expect from a similar vehicle with a standard silencer in average condition. If they believe it is unreasonably above the expected decibel level the vehicle should be failed.

In 2023 the Department published a call for evidence about potential updates to the MOT test including the use of a decibel meter to measure exhaust noise. Although there was some support for introducing such a test a number of issues were also raised. These included the cost of additional testing machines, identifying the appropriate noise level for each vehicle, and the difficulty of testing consistently in a noisy garage.