CHAPTER 7 COMPETITOR VEHICLES AND VEHICLE SAFETY REQUIREMENTS Appendix 8- Exhausts Silencing and Noise Testing
1. Exhausts
1.1. The exhaust system must be isolated from the Driver / Passenger compartment( e. g beneath the floor or secured in casings of solid material).
1.2. No part of the exhaust system on a Racing Car with rear aerodynamic device may extend rearwards beyond the aerofoil.
1.3. If a Racing Car without aerodynamic device must not have exhaust pipes extending more than 600mm beyond the rear wheel axis.
1.4. If Rear Engined Single Seater Racing Car must have the exhaust outlet between 40mm and 600mm from the ground.
1.5. Have all exhaust outlets terminating behind the mid-point of the wheelbase of the vehicle and within 150mm of the outside of the bodywork periphery in plan view.
1.6. Side exhausts must not protrude more than 40mm.
1.7. For Vehicles other than Racing Cars that are not fitted with enveloping bodywork any side exhaust must not extend beyond the plane through the outside of the front and rear tyres with the front wheels in the straightahead position. Cars of Periods A to E and Drag Race Vehicles are exempt from these requirements.
1.8. Exhaust catalytic converters must be fitted to all petrol engined production-based saloon touring and Sports Cars including specialist production and kit cars manufactured after 31 / 12 / 99. They may be specified for certain other Formulae. Competitors are reminded of their obligation to maintain such equipment on a Vehicle used on the highway where government legislation requires it.
1.9. Exhausts must not protrude to the rear of the bodywork more than 15cm.
2. Silencing
2.1. The reason for Silencing( NOISE CONTROL) is to reduce environmental impact and to keep Motor Sport running. Environmental Protection legislation has increased the pressure on activities generating Noise and Local Authorities have the power to suppress any Noise source deemed to be causing a nuisance. Our system of control is acceptable to most Environmental Bodies and must be considered as part of eligibility to Compete in Events.
2.2. All competing Vehicles are subject to mandatory silencing unless a specific waiver for that Class or Formula is granted. Where specified as mandatory a silencer must be used irrespective of the exhaust Noise generated without it.
2.3. Vehicles which comply with the Technical Regulations of FIA Formulae and Championships set out in the current FIA Yearbook and other FIA approved Championships, Series and Cups which are participating in races for such Formulae Championships, Series and Cups at Events which have been entered on the FIA International Calendar are exempt from ASN Noise test requirements but must comply with the Noise test requirements set out in the appropriate Formulae Championship, Series or Cup Regulations.
2.4. Silencing is not mandatory in competitions catering exclusively for the following categories of Vehicle but is strongly recommended and may be made mandatory in the Official Documents at the request of the Circuit / Venue owners:
a.
All Vehicles of Periods A to D.( This does not include Events any part of which takes place on the Public Highway where national laws will apply.)
b. Formula 1 and other Single Seater Racing Cars of Periods E and F. c. Drag Race Vehicles.
Motorsport UK 2025 National Competition Rules Version 11
Chapter 7 Appendix 8- Exhausts Silencing and Noise Testing 274