Roush Axle Backs db readings?

inky5.0

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Hi, I’ve just read about (Cambridgeshire) Police stopping bikes and cars for loud exhausts. Does anyone know the db levels from Roush axle backs? I believe that the legal limit for road cars is 74db. Thanks.





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Adam83

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Last time I did mine it was 98db with Roush axle backs :giggle: got beat by a C63 AMG and a Maserati which both got over 110db!
 

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Modified moped exhausts are the worst, they are loud and sound sht
 

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RE: noise from exhaust


The one most important thing to remember is that you are instantly illegal in every sense the moment you change anything away from stock.


Silencers
54.—(1) Every vehicle propelled by an internal combustion engine shall be fitted with an exhaust system including a silencer and the exhaust gases from the engine shall not escape into the atmosphere without first passing through the silencer.

(2) Every exhaust system and silencer shall be maintained in good and efficient working order and shall not be altered so as to increase the noise made by the escape of exhaust gases.

(3) Instead of complying with paragraph (1) a vehicle may comply with Community Directive 77/212, 81/334, 84/372 or 84/424 or, in the case of a motor cycle other than a moped, 78/1015.

(4) In this regulation “moped” has the meaning given to it in paragraph (5) of Schedule 9.

https://www.legislation.gov.uk/uksi...xhaust system and,the escape of exhaust gases.



Obviously technically and legally, if they (Police and authorities) want to go by letter of the law, if you are running a vehicle that does not comply with Construction and Use Regulations, your vehicle is deemed un-roadworthy, and therefore illegal.


After that noise levels are a bit moot, however the official type approved noise level of Mustangs are as below.

Manufacturer Model Description Transmission Engine Capacity Noise Level dB(A)
FORD Mustang Model Year Pre 2020 2.3 EcoBoost Convertible M 2261 71
FORD Mustang Model Year Pre 2020 2.3 EcoBoost Convertible A 2261 71
FORD Mustang Model Year Pre 2020 2.3 EcoBoost Fastback M 2261 71
FORD Mustang Model Year Pre 2020 2.3 EcoBoost Fastback A 2261 71
FORD Mustang Model Year Pre 2020 5.0 V8 Bullitt Fastback M 5038 73
FORD Mustang Model Year Pre 2020 5.0 V8 Convertible M 5038 74
FORD Mustang Model Year Pre 2020 5.0 V8 Convertible A 5038 74
FORD Mustang Model Year Pre 2020 5.0 V8 Fastback M 5038 74
FORD Mustang Model Year Pre 2020 5.0 V8 Fastback A 5038 74
FORD Mustang Model Year Post 2020 2.3 EcoBoost Convertible M 2261 71
FORD Mustang Model Year Post 2020 2.3 EcoBoost Fastback M 2261 71
FORD Mustang Model Year Post 2020 5.0 V8 Bullitt Fastback M 5038 73
FORD Mustang Model Year Post 2020 5.0 V8 Convertible M 5038 74
FORD Mustang Model Year Post 2020 5.0 V8 Convertible A 5038 74
FORD Mustang Model Year Post 2020 5.0 V8 Fastback M 5038 74
FORD Mustang Model Year Post 2020 5.0 V8 Fastback A 5038 74

Fine more data regarding official emissions etc here

https://carfueldata.vehicle-certification-agency.gov.uk/downloads/default.aspx

So pretty much officially 74 dB(A) is the max legal limit for all Mustangs
 

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i did a track day where they measured the DB at 4k RPM and mine was 95DB. Just to note i'm literally just stock except the roush ABs on the exhaust front, there was a guy there with a pony which was literally straight piped and on silent mode he blew 110DB... then he went track mode... and got banned from the track day lol
 
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inky5.0

inky5.0

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i did a track day where they measured the DB at 4k RPM and mine was 95DB. Just to note i'm literally just stock except the roush ABs on the exhaust front, there was a guy there with a pony which was literally straight piped and on silent mode he blew 110DB... then he went track mode... and got banned from the track day lol
Oh! Fingers crossed that I don’t get stopped...
 

Chappers

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Oh! Fingers crossed that I don’t get stopped...
i wouldnt worry about it, they'll probably be appreciative of the V8 burble rather than a young lad in an old honda civic blowing 110dbs... as long as you're not on Wide open throttle haha :like:
 

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i wouldnt worry about it, they'll probably be appreciative of the V8 burble rather than a young lad in an old honda civic blowing 110dbs... as long as you're not on Wide open throttle haha :like:
i just thought, isnt the max legal 95db anyway?
 

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My mustang with catback is quiet as a mouse. Hardly louder than stock and certainly under most track day limits. The Maserati biturbo on the other hand was well over the limit for Goodwood until I did the noise test at 3k, but that was almost unsilenced from the turbos to the tips with no cats to calm things down.
 

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I'm running Roush axle backs, H pipe and headers, it's loud if you floor it but fairly quiet cruising at low rpm.
 

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So.. a mate of mine has just come around with a decibel reader he bought at Aldi/Lidl, cost £10 or so.

My Mustang has an MBRP street version cat back. It's a 3" stainless with H-pipe, no other mods. It's not overly loud compared to some others.

Anyway... On cold start it is 88db, settles to 78db on idle, then 95db at 2k steady revs, blipping the throttle got 101db. Didn't rev it hard, engine hadn't warmed up.

So assuming that most of us who have cat backs are gonna over the 74db limit.
 

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So.. a mate of mine has just come around with a decibel reader he bought at Aldi/Lidl, cost £10 or so.

My Mustang has an MBRP street version cat back. It's a 3" stainless with H-pipe, no other mods. It's not overly loud compared to some others.

Anyway... On cold start it is 88db, settles to 78db on idle, then 95db at 2k steady revs, blipping the throttle got 101db. Didn't rev it hard, engine hadn't warmed up.

So assuming that most of us who have cat backs are gonna over the 74db limit.
Just done mine on normal cold start 101db settles to 84db in normal mode then down to 75.2 in quiet mode standard exhaust plus h pipe but check my video
 

jord79

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The EU limit on noise, which also appears to have been adopted by the UK is 74dB (at Type Approval). It seems altering exhaust components to be any noisier than at type approval is illegal. What isn't clear is if replacing components (i.e fitting aftermarket silencers or cat-back systems) is the same as altering. Regardless, since stock is at the dB limit for most GTs at least, there is no room, legally speaking, for maneuver.

Falling foul of a roadside test may be a different matter. The noise level recorded at type approval is done through a sophisticated test of varying engine speeds and loads in 'real world' and more controlled settings. The results are then averaged out and weighted accordingly, so I don't see how a roadside test can accurately prove whether or not the sound levels of any particular vehicle are over the limit with any degree of accuracy - there must be quite a bit of tolerance on any arbitrary test equipment to allow for this, meaning there probably is a bit of headroom for mild exhaust modifications.

Interestingly, motorcycles are allowed up to something like 86dB (depending on engine size). I don't know why it's different for them unless it is particularly difficult to silence motorbike engines.
 

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