NC headers, how cheap do you go?

NC1 2.0 aftermarket header options. I’m guessing the ebay ones won’t make as much power, they design looks more restrictive.

The racing beat header comes with the extended o2 sensor cable. Seems like my preferred option but I know very little about headers or mx5 tuning.

I’m not sure how ‘cheap’ you go, but I can speak from experience about a BBR header and Cobalt rear box. I fitted them to my NC the weekend before last.
Certainly not quiet, but has a lovely deep burble and bark. Far more throaty than some of the other combinations I researched.
The installation required a re-siting of the O2 sensor into the mid-pipe and an extension of the cable, as detailed widely elsewhere.
It’s a bit of a pain, as you need to weld the location nut onto the pipe, although I have seen bolt on versions, similar to exhaust repair brackets, if you don’t have access to a welder. The cable can be bought as an extension kit [IL Motorsports), but extending the wiring isn’t difficult.
Alternatively, you can code the O2 sensor out.
I paid £300 for the 4-1, although it was used. It had been installed for only a 20 mile experiment by the previous owner, before being taken off and sold to me. Bargin!

Don’t bother with the first two, the others are all much better and probably not a lot between them.

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I didn’t realise this, for some reason I thought the mid pipe already had a bung for it. I guess it would be best to get that sorted first and have an exhaust shop install a o2 bung and cap it, then when I come to install the headers it’s all there waiting for me.

I thought as much. MX5parts do the I.L one with the o2 extension cable for £405 delivered, seems like the best deal by far.
Would you say it’s best to replace the gasket between the engine and manifold or reuse the original one?

Also I.L do a 4-2-1 and 4-1, would it be right to say the 4-2-1 would give better mid range and the 4-1 probably higher peak power?

The original gasket is reusable over and over again, BUT it depends on how good the flange on the manifold is. If it’s warped it’ll blow and will either need facing to make it right or a thick gasket to take up the difference.
IIRC the IL comes with a thicker gasket, but ask them and the only poor manifold (warped) I came across isn’t on your list.

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I have the car booked in at the local exhaust place, they will unbolt the midsection and weld on the bung, very expensive for what it is but at least it will be sorted for when I install the headers.

The expert advice I received is that the 4-2-1 is lets say “Not that good”.
That information was given from extensive testing by Skuzzle (at the time).
He basically stated not much difference between the IL or the RB, but “marginally” the IL produced better results.
The welding “apparently” is a work of art on the RB too. (The IL one is far from shabby mind).
But you can’t see a great deal anyway.
Stick with either the IL Motorsport or the Racing Beat 4-1.
No knowledge whatsoever on the BBR one, but surely it must be good, as above??
Does that one not have “The Bung” for the sensor incorporated?

I can’t be 100% sure, but I don’t think I have a sensor or indeed a bung welded on the mid section at all.
(See pics of the IL one attached). It was all done on the header itself, hence the supplied long lead.

Agreed the original exhaust manifold gasket is a good one and can be used again.

Clearly a matter for your good self.
Just some research I did before having mine done.

Just for clarification, my set up is a IL header, standard mid section with the cat and a Cobalt SS rear box.

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You’re right, the MX5 parts I.L header shows 2 ports on the manifold, I guess I got confused with the racing beat option as it was my original choice but then VAT and postage kicked in! You just saved me £70 (which is what the shop was going to charge to weld on a bung)

I was also under the impression the sensor would throw a code because it’s measuring the same exhaust gases, I.E it’s no cleaner on the 2nd sensor as there’s no cat there so the emissions will be exactly the same.

I was going to spray it with VHT paint, do it black so it looked more OEM, standard for the MOT.

Did the other original sensor have enough wire to reach?

Mine will be the same as yours then, I.L 4-1, OEM Mid with Cobalt.
Will be the first time I have splashed out on car stuff other than general servicing for probably 5 years.

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Send me a Christmas card😂
I know that mine was coded out etc etc during the remap.
I also know others have fitted and sorted it out themselves.
Also just be “aware” that if you get problems with the lead it might be because it was wired up the wrong way around at the factory. He had to take it apart and sort it.
Enjoy :+1::slightly_smiling_face:

Awesome, thanks for your help!

Mx5 Christmas card, covered in chrome.

Will be skuzzle fitted and remap after.

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So Nick is doing it?

I don’t have a tuner yet. I’m in the SE of London, is Sanspeed near me who are Master EcuTek distributors or AbbeyMotorSport.

I will give Nick a call though and see what he’s able to to :+1:

I meant to say I need to install my Skuzzle and then get the car remapped.

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The 2nd sensor should be in the midpipe after the cat if it is to function properly. If you are going to " map it out " it doesn’t need to be fitted in the pipe at all. The existing cable for the primary sensor will reach the boss in the collector if the wire is disconnected from the cable retainer on the side of the block and re jigged.

That is what I was confused about.

On MX5parts I.L header page it states

“These are now supplied with an oxygen sensor relocation kit which is required to fool the ECU into thinking the first cat is still there and stopping the MIL light coming on. You will need to install a bung behind the second cat and using the supplied wiring harness, move the second O2 sensor down, after the secondary cat.”

The car will be remapped but not right after the headers are installed.
Seems what you’re saying is if I just put the first sensor in the top bung and then cap the 2nd bung and it should be okay? It will probably throw an EML code but should run fine and can be mapped out later.

This is the info I used. The new threaded boss was welded in a horizontal plane just after the midpipe cat. The position should be chosen and marked on the pipe whilst still mounted on the car to verify the protrusion of the boss and fitted sensor don’t contact the ppf frame or other underbody parts.

Seems it will be okay without the alterations of the mid pipe, just means I should talk to a tuner and see if mapping out the sensor allows other errors to the be detectable and have the fault system work as intended.

“Although the MX5 will continue to operate normally with the light illuminated (and an error code triggered), driving with the light illuminated may prevent detection of another engine related problem that may occur during the race event”

I don’t have much time to write lately, but just to say in my experience of this it’s all good info you’re getting and discussing here, I have nothing much to add.

I have an IL motorsport 4-2-1. Power comparable to the 4-1 but would favour a 4-1 with long primaries if I had brought one. After the previous owner made a poor job of fitting the extension to the second sensor which melted on the pipe and blow the ecu fuse, BBR mapped out the sensor. I have had no issues and was advised the input from the sensor is not required.


Awesome thanks.

I will go down the route of mapping out the sensor.

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I bought my ILM headers, they have just arrive at mx5 parts from the Deutschland!!

I wanted to know about o2 sensors, the ILM headers have 2 ports but I will be deleting the o2 sensor(s) via remap.

Do I need to install them both in to the ILM header and then let the remapper remove what they need to?

Can I remove both and drive the car with the 2 ports plugged without issue?

What I expect is I will still need the primary sensor in one of the ports but that I would be able to totally disconnect and remove the secondary sensor without issue?

I don’t want to come to installation and realise I’m bugged due to a small detail.
I realise I will probably need to cut the primary sensor wires and extend them a little bit.
The ILM kit comes with an extension but only for the secondary sensor.