Is the stock 2018 Mustang GT active exhaust technically illegal in the UK?

[drewzh]

I haven't seen this discussed anywhere else already, so I thought I'd raise the topic as I'm intending to install a H pipe very soon and on researching exhaust decibel laws in the UK, it seems the law gives a higher end of 90dB for any standard car. From viewing sound comparison videos on YouTube (specifically the American Muscle video attached at the bottom), I can see that the standard exhaust kicks out upwards of 100dB in 'Quiet' mode alone?

In 'Sport' mode they give a reading of 113dB, which is 23dB over the current UK legal limit. Obviously track mode doesn't count here as it's only intended for track usage, but that gives a readout of 115dB, which is odd considering from quick research, most tracks in the UK won't allow anything over 105dB!

Now I know from 'spirited' driving, the GT in track mode sounds very loud. I have had friends comment that they can hear me coming from down the road, so I was always a little skeptical about how 'legal' the GT is in regards to dB laws.

I guess the question is... how is this possible? Surely a car coming from the manufacturer should be 'legal' in any mode?

I guess that somehow, Ford was able to slip passed the road laws with the readouts from 'Quiet' mode alone and for whatever reason, they didn't register with the same readings that American Muscle read in their comparison videos. Maybe there's differences from the US exhaust due to header design etc perhaps? When my GT goes to the shop in a few days, I'm going to take my dB meter anyway for a few 'before' and 'after' recordings to confirm.

Now I know the H pipe that I'm intending to install is going to throw this off even more drastically - I think generally it'll roughly add +5dB, so I'm going to be very mindful of cold starts; I'm aiming to put the car into perm 'Quiet' mode startup and save Normal/Sport/Track for open roads where I'm less likely to offend anyone or get the attention of the police.

My intention with the H pipe isn't for volume, it's more for the sound characteristics, i.e, the low level rumble and potentially add a bit more 'character' with 'pops' and 'burbles' etc. Maybe there's something else I can do at a later time to bring the volume down if I'm ever ticketed? I intend to keep the original resonator anyway that I can quickly clamp back in if needs be.

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[Gregs24]

Plenty of cars over 90db. My Evora struggles to get under the 105db track day limits with the valve open and the Evora 400 is even louder. I imagine it will have been tested with the valve shut in quiet mode.

If you look on your V5 you will see the official figures for your car (static and drive by)

 

[melwff]

Could the testing criteria be different between what Ford does for the UK versus how American Muscle performed the test? What is the distance from the vehicle for UK versus AM? What is the angle of the measurement UK versus AM? Those are just two variables that come to mind and there may be others.

 

[Toecutter]

Had too many comments from neighbours about how loud the car is.
I have quiet mode set from 8 to 8 but put it into track mode as soon as I turn out of my estate.
Still ignore the warning that it's 'For track use only ' every time I do it because I'm such a badass.

 

[Adam83]

Had too many comments from neighbours about how loud the car is.
I have quiet mode set from 8 to 8 but put it into track mode as soon as I turn out of my estate.
Still ignore the warning that it's 'For track use only ' every time I do it because I'm such a badass.

Woah save some pussy for the rest of us

Mines permanently loud with the Roush fitted, my neighbours can f**k off

I did wonder about noise levels but surely unless it states “for off road use only” on the exhaust it must be road legal right?

 

[Manders Mustang]

Woah save some pussy for the rest of us
Mines permanently loud with the Roush fitted, my neighbours can f**k off

Woah save some pussy for the rest of us

 

[Steeda UK]

I see a theme developing here......

 

[Gregs24]

There is no upper limit in the UK and if the vehicle is fitted with the oem exhaust from the manufacturer, that was type approved, then it is legal full stop. It’s illegal to modify the exhaust system to make a vehicle noisier after it has been ‘type approved’ which means an aftermarket exhaust cannot be legally louder than the oem one.

 

[hinch]

There is no upper limit in the UK and if the vehicle is fitted with the oem exhaust from the manufacturer, that was type approved, then it is legal full stop. It’s illegal to modify the exhaust system to make a vehicle noisier after it has been ‘type approved’ which means an aftermarket exhaust cannot be legally louder than the oem one.

I think every single aftermarket exhaust is louder than oem isn't it

 

[Adam83]

Has anyone else seen the new law in California? Any car found to have a modified exhaust making it louder gets a $1000 fine?! Came into play jan 1st, so glad I live in sunny Yorkshire

 

[drewzh]

There is no upper limit in the UK and if the vehicle is fitted with the oem exhaust from the manufacturer, that was type approved, then it is legal full stop. It’s illegal to modify the exhaust system to make a vehicle noisier after it has been ‘type approved’ which means an aftermarket exhaust cannot be legally louder than the oem one.

Then what about this these seemingly legit looking sources stating that the decibel level IS enforced?
https://www.vehicle-certification-agency.gov.uk/fcb/cars-and-noise.asp
https://www.essex.police.uk/getmedi...d07/H0504-Procedure-Loud-Exhaust-Offences.pdf

 

[drewzh]

Has anyone else seen the new law in California? Any car found to have a modified exhaust making it louder gets a $1000 fine?! Came into play jan 1st, so glad I live in sunny Yorkshire

It seems california have it even worse than we do. A 1K on-the-spot fine without any proof that it's actually not stock. It just takes a cop to 'think' it's too loud! I hear a stock M4 and a stock Mustang have been fined so far and it's on the owner to take it to court to argue and present evidence. I imagine the time out of work alone would be in the thousands for some of us, it's crazy.

 

[Manders Mustang]

Then what about this these seemingly legit looking sources stating that the decibel level IS enforced?
https://www.vehicle-certification-agency.gov.uk/fcb/cars-and-noise.asp
https://www.essex.police.uk/getmedi...d07/H0504-Procedure-Loud-Exhaust-Offences.pdf

but the stock exhaust is louder than 76 lol.

There's a rule on stock exhaust and modifying it, however the loop hole is, if it's all nolonger the stock exhaust (from the manifold back) then it's not a modified OEM exhaust it's a replacement modification.

 

[SteveS]

but the stock exhaust is louder than 76 lol.

There's a rule on stock exhaust and modifying it, however the loop hole is, if it's all nolonger the stock exhaust (from the manifold back) then it's not a modified OEM exhaust it's a replacement modification.

So has to be a complete system (ie manifold as well) or just a catback?

 

[drewzh]

but the stock exhaust is louder than 76 lol.

There's a rule on stock exhaust and modifying it, however the loop hole is, if it's all nolonger the stock exhaust (from the manifold back) then it's not a modified OEM exhaust it's a replacement modification.

How certain are we of this 'loophole'. Is there any write up discussing the technicals etc or is it just hearsay? I've seen a few sources say it simply can't be louder than what came from the factory.

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