I have an Audi A6 C6 4F2 - 2.4L V6 and I'm wondering if I should put in a cold air intake.

As seen on the picture right here (left side), there isn't much space.. I was thinking to put the aftermarket intake inside of the 'original' box to avoid engine-heat to get sucked up as well, however I'm not sure if this would be of any benefit whatsoever.

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Should I

  1. Keep the stock cooler, don't put in the cold-air intake
  2. Put the cold air intake inside of the box (completely sealed)
  3. Put in the cold air intake and remove the box. The intake would be hanging (stable, however), but would suck up engine heat as well (assumingly) but might not get the direct air as if it were inside of the box..

I had an cold-air intake in my A4 B5 and it sounded amazing, even if it weren't beneficial. (Haven't dyno'd it, so I can't prove it gave more/less power)

2 Answers 2


tl dr: You have to make the call if an aftermarket CAI is right for your car. We can't make the decision for you.

With that said, an informed consumer is a wise consumer.

There are three purposes behind a cold air intake (CAI):

  1. Allows for better airflow - You see the bellows just after your air filter now? All of the ribs there create a huge amount of turbulence and restriction. A "typical" CAI will smooth out the air flow and reduce the restriction. The idea of an aftermarket conical filter also helps reduce restriction.
  2. Allows for cooler intake charge - It used to be air was brought in from under the hood. The air is typically heat soaked. We all know, hot air (in most normal cases) is not as good as cool air, and thus reduces power. By drawing air from outside of the engine compartment, cooler air is introduced into the engine.
  3. It looks better - Most cars can benefit from this as stock air intake systems are black, plastic, and ugly (MHO, lol).

Looking at your engine compartment, it looks like #2 would be negligible. It appears it is already pulling air from outside of the engine compartment. In most cases as far as aftermarket CAI's go, the filter element ends up being right in the engine compartment which negates one of the intended effects of a CAI in the first place. If you are considering using the piping from a CAI instead of the stock piping, then leaving the air box in place, this may be a good option as long as it fits and can be sealed. If you are to do this, the black baffling/piping would need to go because more than likely there'd be no way to fit aftermarket piping into it. A free flowing air filter should be able to be fit into the air box, but it all depends on how it's made and its shape.

Aftermarket CAI's can suffer from heat soak, even if the filter element is not drawing air from inside the engine compartment. In fact, heat soak is usually not considered the air which is drawn into the engine from the engine compartment, but rather the hot air from the engine transferring to the intake tubes which are open to it in the engine compartment. This happens a lot more to those intake tubes which are metal versus some sort of composite material. You'll find the metal tubing is lot cheaper than composite because it's a lot easier/cheaper to make. Thin walled aluminum is really easy to produce in the right shape and is used by most of the "eBay" manufacturers/sellers because of this. The composite ones take a lot more work to get them right. You'll usually find these are of a lot higher quality than the metal ones.

The filter elements are the other concern. Just because you have a conical filter element doesn't mean it will flow better than stock. You should be able to trust manufacturers such as K&N, as they have a pretty solid reputation with their filters. Reusable filters which can be cleaned are a plus, as you can, over the life of your car, have the CAI pay for itself with the savings on purchasing replacement filters. (NOTE: Some will complain about the oil from filter elements such as K&N causing problems with their MAF or other intake sensors. If the oil is applied correctly, there is no issue. People get over exuberant with the oil, and/or don't wait for it to dry. This is what causes these issues, not the oil in and of itself.)

The big thing to remember here is all CAI's are not made the same. Some are going to be better than others. You'll have to do your due diligence to figure out if any of them might be right for your car and perform as you'd expect. Just don't believe everything you see on the internet as far as performance gains and such. Most aftermarket CAI's will be louder (as you've suggested), so keep that in mind.

Mostly, keep all of your stock "stuff" intact ... you may decide you don't like the CAI and want to go back to it. If you destroy it or throw it away, you won't have the option of going back to stock without purchasing new.

  • This is the perfect answer, @Paulster! Thank you very much. I do have metal piping as well, but prefer the stock ones way more as they don't get as hot as the metal ones, from experience (old car). My current CAI could almost sit perfectly inside of the box, with the box being sealed. So basically I'd be swapping the current air filter for the 'mushroom'. Would you recommend this? In terms of sound, I like it as it is subtle, not too loud. (I hate fart cannons and rather have a well-sounding engine). In terms of power, I'm not seeking to get tons of HP,just want the engine to breathe nicely:)
    – Paramone
    Commented Dec 29, 2017 at 15:25
  • @Paramone - This is really up to you. Personally, I have to look at what is there then compare to what would be going in place. Every car is going to be different, and every CAI is going to be different as well. Remember, though, the filter is just a filter: a CAI is the complete deal, usually running from filter to throttle body. Just saying. Commented Dec 29, 2017 at 15:29
  • Ah, alright. I'll have to do a bit more research then! What kind of tests could I do to compare ? Such as; Air-temperature, air-flow, oxygen levels (if this is possible)?
    – Paramone
    Commented Dec 29, 2017 at 15:31
  • 1
    @Paramone - Unless you have the test equipment, you'd have to take it to a dyno shop to have them run one against the other. Since you aren't worried about HP gains, get what seems right to you. You can pull live data from the ECU if you have an OBDII reader which is capable of it. This would give you the Intake Air Temperature readings before/after. You could also get MAF readings at different engine speeds and see how the O2 sensors are behaving. Again, you'd need a code reader capable of reading live data. If you have more questions, please feel free to ask a new one as a separate question. Commented Dec 29, 2017 at 15:35
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    I like the comment about keeping the old parts. While you may think the extra noise from the air intake is cool the next owner may not.
    – mikes
    Commented Dec 29, 2017 at 16:58

It all depends on what you want, the choice is for increased or the same engine protection - stay with stock basically.

Or you want a less restricted air flow so an aftermarket filter but reducing the restriction increases the particles “eaten” by the engine likely to increase wear - but that also depends on how long you keep the car etc...

This makes good reading as they tested various filters under controlled conditions - better than those who say “I fitted X and got Y, so it is the best / worst / fastest etc” : https://www.fastcar.co.uk/tuning/performance-car-air-filter-test/

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