Exhaust system?

Hello all,
Just after a bit of advice and guidance please; I have a 2008 NC 1.8, I’d like to change the exhaust system and have no idea what’s good or bad, pricey or cheap to avoid. I am not wanting to rattle the neighbours windows just something with a nice noise and a few more BHP is a bonus?
All assistance appreciated.


Just the back box (most seem to ask about that) or the whole system?

That’s the thing I don’t want to spend a fortune but would like a subtle improvement so if just a back box is all I need; I can check oil inflate tyres and change bulbs but no master of the spanners or knowledge underneath I’m afraid, :blush:

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This rear silencer will improve the sound of your MX5. There are many recommendations by members on the forum for this silencer. The silencer is not overly loud and does not drone at motorway speeds but has a nice sporty sound. I fitted one on my MK3.5 a few months ago and I’m very pleased with it.
It takes a few hundred miles for the silencer to settle into a nice sporty sound.

The fit and alignment of the twin tailpipes is very good, included with the silencer is a gasket and nuts and bolts.

Moss often have price reductions on their items, so worth keeping an eye on their website.


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As the post above if just a back box. I have the Cobalt, it’s as described in that post, gives a more sporty note without being overly loud. I’ve had mine fitted for around 4 years and been on long motorway journeys and it doesn’t drone but it is louder than the standard box. Just to add, I bought the Mx5parts SS back box and that had to be removed, far too noisy and droned badly, not for me.:-1:

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Backbox change for sound difference and recommend trying a car with one on in your type of typical driving conditions before purchase. So many people either sell a box or put up with it where they have made the wrong choice.
The most difficult exhaust change for considerable extra horsepower(at least 10 I believe) is replacing the maniverter with a combined front pipe/manifold.
Contentious because it removes one of the catalytic converters that in theory should fail the car at MOT time as original system as intended not in place. Not aware of anyone pulled up on this technicality…yet.

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When I had my mk3 1.8i I changed my back box to a cobra :snake: sport was just enough pops on down shift , had a lovely burble too , there is YouTube vids on sounds etc , cobalt nice but not much different to OEM in my opinion best of luck whatever you choose :+1::rainbow:

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Hi, I would agree with the Cobalt box all day long.
Comes with new gasket and bolts too.
VERY easy to fit.
I did have the Go Perform box, but quickly took it off and sold it.(Did look nice though).
Too noisy and did drone at motorway speeds.

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I agree with all above regarding the Cobalt back box, I have one fitted and it looks great, sounds much sportier than the standard one, but not too "in your face " and after a few hundred miles it settles to a more subtle deeper sound



Thank you everyone for the recommendations, certainly gives me a good idea what to go for.

Stay safe and enjoy any roof-down action you can get now BoJo has relaxed a little :+1:

Another vote for the Cobra back box here - the grey NC on their website and You Tube is actually my old mk3 as I took it to them to have a race back box fitted at their premises in Sheffield.

Prices seem to have gone up quite a bit since I bought mine, though that was 6 years ago.

Just one observation with changing the back box - some people (including me) have reported vibration/resonance from the rear parcel shelf - there are some threads on here on the subject.



I went a little further I guess and went for the Scorpion cat back system. It deletes the 2nd cat and centre resonator box. It did pass the MOT fine. It is quite a bit sportier on acceleration and does have a nice repertoire of “pops and crackles” on lift off. Cruising under light throttle loads it is not much louder than standard with no nasty droning. Not that I tend to drive on light throttle much, (it’s too tempting just to hear the noise)! Pick up seems quicker, certainly from 3.5k. Mine is a 2005 1.8. I did post a review on this a while ago if you can find it on here.
The guys who fitted it, (ramp very useful) said that it is very well made and wasn’t too much trouble to fit. If you ring Scorpion they can tell you who has them in stock near you or for delivery. I got mine quite a bit cheaper than MX5parts advertise.
Hope this helps
Kind regards

Cobalt here too
i would recommend it all day long i can only mirror the above comments
i did have a Cobra before the cobalt and it was great around town etc but the motorway or a normal drive out it was horrible inside the car and i couldnt wait to get it off the car
each to there own thou
ive used scorpion on other cars but not the MX5 they do make a top quality exhaust system as well but i dont know what there like on a MX5 thou sound wise .

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Also +1 for the cobalt

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Another point to remember is if later on you decide to say have a 4 into 1 manifold the cobalt works VERY well with it noise wise. Only my opinion but anything else will be too loud and annoying. (I learnt the hard way :roll_eyes:). All a matter for your good self though :+1: