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Following some conversation in a thread on Zpost about why all CF intakes don't use the MAF, I contacted Karbonius to see if they would be interested in making a carbonfibre replica of the stock plenum. Below is the response I received from Karbonius. Because this would be a direct reproduction, there would be no power gains and, obviously, it won't be cheap but the intention is that it would provide some of the CSL intake sound without requiring a tune or deleting the MAF. Karbonius (and Eventuri) have done a similar thing for the S65 and it sounds great.

https://www.youtube.com/watch?v=pjQ256lcHGA

I am waiting for a rough cost from Karbonius.

To summarise Karbonius's reply, if we can find 20 people to express an interest in purchasing a CF version of the stock plenum, they will make a test.

If you are interested, please post in this thread or the Zpost thread if you have an account there (https://www.zpost.com/forums/showthread.php?t=1900559). Feel free to post on other relevant board (e.g. E46 M3).

"Hi Michael, thanks so much for contacting us with so interesting topic!! Isn´t the first time someone asking for this!!

Yes, we could do it, but there are any problems with this, the first is the coist of the molds!! an standar mold in GF only to make 20 or 30 pieces , could cost around 3000€, and then the pieces.. this is the first problem..

the second, is until we made the first unit we didn´t know what will be the sound, if louder or lower sound comparing with CSL, at first I would say lower than CSL, and this could be a problem, expend a lot of money on the mold and finally didn´t get the expected sound !!!

We could make a test, but we should have at least 20 interested persons in it!!"

Bit late for me as mines having CF air box and Alpha N next Friday.

If you're keeping the standard air box and filter, then how much extra intake sound do you really expect to gain?

What's the maximum price you'd consider paying for something that might not even give you half the volume increase of a proper CSL-style intake and alpha-n...also taking into account you'll get zero power increase.

What if you pay your £x000 and don't like the sound it makes?

Have to agree with the above. I like the idea but Karbonius aren't known for being particularly cheap and if your spending that amount then you are probably not far off proper CSL box territory so may as well go the whole hog at that point. Don't think Alpha-N has many drawbacks these days if any.

I would say the Gruppe M and Eventuri fill that gap between CSL box and standard so can't see a market for this (at 2-3K+ anyway). Good luck with it though

mmm-five wrote: ↑Sat Feb 19, 2022 3:46 pm If you're keeping the standard air box and filter, then how much extra intake sound do you really expect to gain?
What's the maximum price you'd consider paying for something that might not even give you half the volume increase of a proper CSL-style intake and alpha-n...also taking into account you'll get zero power increase.

What if you pay your £x000 and don't like the sound it makes?

If I bought one I certainly wouldn't keep the stock air filter/box, something like the aFe or Gruupe M intake would work well.
You would get the benefit of the MAF reliability and keeping it exactly where BMW programed it to be, plus better induction sound.
You wouldn't pay any money if you don't like the sound, that's reason for Karbonius making a test intake.

I realise this is going to be a bit niche and not for everyone. As I understand it, alpha-n is a pretty limited way to tune a car and while people have gotten results that are acceptable to them, it still seems like a sub-standard option that could detract from the fun of driving the car (making it a non-starter for me).

The sound issue is a significant one, acknowledged by Karbonius, but if enough people are interested, they will try. I doubt it would be as loud as a full CSL intake by itself but having listened to Eventuri's S65 plenum (with and without the intake section), a carbon plenum on a Clio RS and a carbon plenum on an S14 in an E30 M3, I genuinely think there is a chance it will work to a significant degree on the S54. As @AndyBeech says, Gruppe M and Eventuri (which I already have) offer products that provide a nice boost to the stock sound. Pairing one of these to a carbon plenum could get you pretty close to full CSL sound. However, there may be people that would prefer an essentially stock look in the engine bay (me for one) with some extra CSL-lite sound, which could be achieved without a Gruppe M / Eventuri.

As for price, I have no doubt it will not be cheap and people will need to weigh that up.

If i could still use my eventuri then i would be interested however this would Depend on noise/cost.

Matt.13 wrote: ↑Sun Feb 20, 2022 5:52 am If i could still use my eventuri then i would be interested however this would Depend on noise/cost.

You would still be able to use your Eventuri - the plenum would be the same as the stock item, just made out of carbon fibre, and nothing upstream will change.

I will update the thread as soon as I have a rough cost from Karbonius.

Seems like a niche within a niche. It might add a bit to the sound but ideally you’ll have to pair it with an eventuri or similar to get the most from it I expect.

Although it loses the oem feel, a new, maf compatible lower part that connects to their existing csl plenum would reduce tooling costs and allow you to connect an ‘open’ filter before the maf connection.

The biggest problem I see with it is cost. It’s probably going to be the same price as the csl box and then you’ll need an eventuri. Is it really worth it just to keep the MAF and a slightly more oem look? I’d argue it isn’t as alpha-n isnt the flintstones solution it’s sometimes made out to be and the Karbonious box is already very original looking. Horses for courses though, if there’s demand once the price is better understood then why not.

I'd be interested in this, particularly for the sound benefit and the fact that retaining MAF control of the ecu has several advantages.

Z4MCoupe86 wrote: ↑Mon Feb 21, 2022 8:47 am I'd be interested in this, particularly for the sound benefit and the fact that retaining MAF control of the ecu has several advantages.

Thanks - I’ll add you to the list on Zpost. If the list keeps growing I’ll bring the list to this thread too, just don’t want to maintain two lists right now.

Matt.13 wrote: ↑Sun Feb 20, 2022 5:52 am If i could still use my eventuri then i would be interested however this would Depend on noise/cost.

Matt.13 - I have added you to the list on zpost as well but with a note re the cost (really, we’re all waiting for the cost estimate).

Karbonius has provided a rough price: 1,200 Euro.

I think this is quite reasonable, but have no idea what others' expectations are.

Matt.13 and Z4MCoupe86 - are you still interested at the above price?

Yes

Z4MCoupe86 wrote: ↑Wed Mar 02, 2022 11:30 pmYes

Great - thanks.