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MOT decibel limit


Kaikora

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There is no legal set limit for the MOT, however it should fail if the noise is above what you can expect from a standard car. It’s against the construction and use regs to fit any exhaust that is intentionally louder than OEM too. 
 

In practice as long as you don’t fit straight pipes right the way through and then sit outside McDonald’s banging it off the limiter, you’ll be fine :) 

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Quite a few people have aftermarket exhausts and cats. Not heard of any issues, MOT tester most likely won't care and police won't pull you over for a loud exhaust - you won't be the only one on the road with a louder exhaust :p

 

If you're hooning it around car parks then it'll be totted up on reasons to harass you.

 

Buy it, fit it, enjoy it and don't worry! 

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I have race pipes on my Ducati and it is obscenely loud, but never had any issues with MOT.  I have seen it where the tester has put down as an advisory that "exhaust is excessively loud" before, but never a failure. Speaking to a tester once a few years back they said (at the time) that the rules were a vehicle shouldnt be louder than a similar vehicle. He also did say that as nearly everyone has a sports exhaust on their motorbike then they do all sound the same anyway. 

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You'll never be able to attend a track day...

 

I had a full custom 3" exhaust with resonator centre and 'Jap can' style rear straight through 'silencer' with sports cats and headers built last year and it was around 120db before I had it changed to a chambered rear silencer. Think it maxes around 102db now, and I'm looking to change the centre section to a chambered unit as well.

 

On the original question RE MOT it's down to tester's opinion, same with Police - if you get stopped and issued a ticket, I don't think you can argue it.

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Thank to everyone who gave info, gave me plenty to think about and mull over.

On 17/05/2020 at 20:49, Ekona said:

There is no legal set limit for the MOT, however it should fail if the noise is above what you can expect from a standard car. It’s against the construction and use regs to fit any exhaust that is intentionally louder than OEM too. 
 

In practice as long as you don’t fit straight pipes right the way through and then sit outside McDonald’s banging it off the limiter, you’ll be fine :) 

This is what I could understand from the wonderful vague laws!

 

On 19/05/2020 at 22:58, msitpro said:

You'll never be able to attend a track day...

 

I had a full custom 3" exhaust with resonator centre and 'Jap can' style rear straight through 'silencer' with sports cats and headers built last year and it was around 120db before I had it changed to a chambered rear silencer. Think it maxes around 102db now, and I'm looking to change the centre section to a chambered unit as well.

 

On the original question RE MOT it's down to tester's opinion, same with Police - if you get stopped and issued a ticket, I don't think you can argue it.

I'm not interested in track days, I'm purely for the thrill on the road, plus perhaps being that obnoxious neighbour once in a while.

 

I am contemplating either the Tomei, or just going non-resonated Cobra, as I do feel like as much as the car suits single exit, the bumper doesn't so like the dual exits. Over the years my ultimate goal is NA 350 BHP from a Rev-Up engine, which might cost a bit but I believe is achievable.

 

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13 minutes ago, Kaikora said:

I do feel like as much as the car suits single exit, the bumper doesn't

If you tuck the bumper it can suit a single exit. 

If they're the only 2 you're torn between I wouldn't entertain the idea of Cobra, they're not in the same league in terms of quality. 

 

IMG_0673Medium.jpg

Edited by Jack94
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350hp from a Rev-Up shouldn't be difficult.

 

That's 305-310hp at the wheels which should be achieved with the following shopping list at over 7000rpm:

 

Plenum spacer or Kinetix Velocity plenum (or custom)

200/300 cell 2.5" diameter cats

Stainless larger diameter equal length headers - Tomei for example

2.5"+ Y-pipe branches

3"+ exhaust (Tomei for example)

Jim Wolf S7R cams (http://www.jimwolftechnology.com/wolfpdf/cam_spec_card_vq35_incl_revup.pdf

Up-Rev tune

 

 

On an HR, you save on not having to buy a plenum spacer or headers to make 300whp+...

 

Also agree with Jack on the single exit - needs a tuck or different bumper with flat bottom. I have a Nismo v3 style rear bumper and cut out the lower sculpts/recesses for tailpipes so it's a straight line across.

 

Edited by msitpro
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