intake

[sabb]

so I am looking in to purchasing a cold air intake for my 08 Quattro and I was wondering if there are any that are better than others for our cars? Preferably one that might let my hear the blow off valve go off

[oVeRdOsE]

so I am looking in to purchasing a cold air intake for my 08 Quattro and I was wondering if there are any that are better than others for our cars? Preferably one that might let my hear the blow off valve go off

tons of thread on this.
But imho, custom intake with heat shield.
For a CAI, you need to reach down, out from engine bay.
If not, it's a HAI.

If you want plug and play , you have lot of choices as well. Around 3xx$ to 4xx$

http://www.audizine.com/forum/showthread.php/86411-Carbonio-Intake-Testing-and-Review-for-B7-A4-2-0T-FSI

[1killera4]

Jesus...not again [facepalm]

[miA4]

I've read that these don't make a difference performance wise. They cost a bit of money for no actual results. for the cash, you'd be better off with spending a bit more for a stage 1 tune. as far as hearing the blow off valve go off....... I can't help you there.

[UberTeile]

Installing any kind of cone filter/piping set-up might let you hear the turbo spool. If blow-off/DV noise is what you're looking for, I think you'll need one of these...

https://www.ecstuning.com/Audi-B7_A4-Quattro-2.0T/Engine/Turbocharger/Blow_Off_Valve/ES1832412/

[Okedokey]

Jesus...not again [facepalm]

Why even post this. There are new people that are interested in a discussion specific to their requirements.

I know the current mantra is that it makes no difference, however I found this http://myweb.wit.edu/brouillarde/Senior%20Design%20Files/Senior%20Final%20Report.pdf

Which shows that done correctly, it will make a difference.


After conducting the multiple tests and simulations the data has proven that the new design of the custom air intake assembly will allow for greater air flow and cooler air inlet temperatures. The overall goal of this project was to design and build an air intake assembly that could outperform the current factory assembly found in the 2008 Audi A4 B7 platform. After building, modelling, and testing the new custom air intake assembly it is safe to say that it does outperform the factory intake.

http://i1112.photobucket.com/albums/k495/bigfellla1/Capture_5.png~original

[TheTrith]

Was that graph recorded on a stationary car? Or while driving on the freeway?
That looks like a max intake temp difference of about 7 degrees. How much power does that translate to?

[Charles.waite]

Why even post this. There are new people that are interested in a discussion specific to their requirements.

I know the current mantra is that it makes no difference, however I found this http://myweb.wit.edu/brouillarde/Senior%20Design%20Files/Senior%20Final%20Report.pdf

Which shows that done correctly, it will make a difference.



http://i1112.photobucket.com/albums/k495/bigfellla1/Capture_5.png~original

You're making the assumption that our current intake is ingesting hot air. Its not. And since the intake is directly over the catalyst you're only ever going to get hotter air from inside the engine bay.

[Okedokey]

You're making the assumption that our current intake is ingesting hot air. Its not. And since the intake is directly over the catalyst you're only ever going to get hotter air from inside the engine bay.

Your point is contradictory and doesn't change anything presented in the paper. I'm not making any assumptions. I am presenting a university assessment showing the difference between stock and custom CAI on a A4 B7. Just because it contradicts your world-view, doesn't make it wrong. Read the paper - the air intake is via the fender well, not the engine bay.


Overall the goal to increase the air flow efficiency and decrease air inlet temperatures was successful. With this increase of cooler air flow, the engine is able to take in air much easier which allows for greater engine performance and output.


After building, modelling, and testing the new custom air intake assembly it is safe to say that it does outperform the factory intake. The differences can be seen in the data and graphs in the report. There is a clear advantage to this new design in that it allows for much smoother flow entering the engine, adding the ability to increase its air to fuel mixture ratio.

These are their conclusions, not mine. So unless you have evidence to refute the above, your opinion seems to be based solely on group-think.

[Charles.waite]

Your link doesn't work on my iPhone so I can't read the paper.

I'm skeptical because this is the first I've seen where measurable gains were "proven" by any sort of scientific method.

The stock intake pulls air from the front grille and the wheel well. It's literally a cold air intake. Moreover it simply isn't a restriction for a turbo that pushes MAX 200g/s when completely wound out.

So, yes, I'm skeptical.

[Okedokey]

Sceptical is fine, but again, that's just based on opinion, and commenting on something you haven't read isn't a great idea. The issue found with the stock intake is that the mass flow is restricted causing a vacuum on the intake. The frontier boundary is too restrictive.

The results also show a better lamina flow on the custom aftermarket CAI,
there is a much smoother and less restrictive flow in the custom when compared to the factory intake. The reason being is because the factory intake requires higher air velocity to achieve the same mass flow rate of 0.16 kg/s. This basically means that the engine is working harder to achieve the same mass flow rate. Also another interesting fact when looking at the surface parameters for the tube lids is the difference in pressure between the two intakes. The factory intake has a lower pressure than the custom intake. This further proves to the fact that the engine is working harder because there is stronger vacuum in the factory air box. allowing for better power delivery compared to the stock CAI because:


The results show that an inflow-condition without any perturbations gives the highest shaft power output, while a turbulent flow with a strongly swirling motion at the inlet results in the lowest power output. In: PROCEEDINGS OF THE ASME TURBO EXPO 2008: Power for Land, Sea and Air, 2008, Berlin, New York: AMER SOC MECHANICAL ENGINEERS , 2008, 1985-2001 p.

You want further scientific evidence?


However, experiments on a turbocharger test bench show that, contrary to general opinions, the heat transfers can influence the turbocharger performances. Heat Transfers Characterisations in a Turbocharger: Experiments and Correlations, Paper No. ICES2006-1324, pp. 53-64; 12 pages doi:10.1115/ICES2006-1324


This data identifies the strong effect of the heat transfer on the apparent efficiency of the compressor and turbine, particularly at low speeds and low mass flows. A simplified theory is used to explain the apparent effect of the heat transfer on the work input and efficiency. The results confirm that conventional performance maps underestimate the efficiency of the compressor stage and overestimate the efficiency of the turbine by as much as 20% points at low speeds. Morel, T., Fort, E., and Blumberg, P., "Effect of Insulation Strategy and Design Parameters on Diesel Engine Heat Rejection and Performance," SAE Technical Paper 850506, 1985, doi:10.4271/850506.



Heat transfers in an automotive turbocharger comprise significant energy flows, but are rarely measured or accounted for in any turbocharger performance assessment. Existing measurements suggest that the difference in turbine efficiency calculated in the conventional way...differs considerably from the usual diabatic test conditions, particularly at low turbine pressure ratio. Hellström, Fredrik KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. 2010 (English) Doctoral thesis, comprehensive summary (Other academic)

There's tonnes more out there...

[Charles.waite]

Pretty sure this thread was headed in the direction of "if I put a spectre foam filter directly onto my MAF will my car be super fast and go whoosh???"

Not academic research into the physics of airflow...

Also: http://dictionary.reference.com/browse/skeptical

FYI it's also spelled with a k. I daresay it's more frequently spelled with a k than with a c since the c variant is a British word.

[Okedokey]

I see, the English don't know how to spell English words ;)

You asked for mesureable performance gains (evidence based) and I gave that. The point is, he's talking about a CAI and the view on this forum is that it is pointless. This is not backed up by actual assessments from the scientific community. The value for money argument however... I'm on your side. ;)

[Charles.waite]

It's pointless because we do in fact have a cold air intake from the factory. And then we have a really hot hairdryer heating that air up like crazy. You'd see far more gain investing in a good IC and routing the airflow to that IC properly than you ever would messing with the intake.

[Okedokey]

Its not necessarily one of the other. The point is, colder air into a turbo increases performance. Whether its value for money isn't the question.

[1killera4]

Why even post this. There are new people that are interested in a discussion specific to their requirements.

I know the current mantra is that it makes no difference, however I found this http://myweb.wit.edu/brouillarde/Senior%20Design%20Files/Senior%20Final%20Report.pdf

Which shows that done correctly, it will make a difference.



http://i1112.photobucket.com/albums/k495/bigfellla1/Capture_5.png~original How about because it's been beat to death in this forum?

And who wants to cut a hole in their fender for such a minimal gain? Brilliant!

[Okedokey]

How about because it's been beat to death in this forum?

And who wants to cut a hole in their fender for such a minimal gain? Brilliant!

The cold air intake is already on the car from the fender.

Just because it has been beaten to death, doesn't make it correct. If you don't like the discussion, easy, unsubscribe.

[07AudiA42.0T]

Installing any kind of cone filter/piping set-up might let you hear the turbo spool. If blow-off/DV noise is what you're looking for, I think you'll need one of these...

https://www.ecstuning.com/Audi-B7_A4-Quattro-2.0T/Engine/Turbocharger/Blow_Off_Valve/ES1832412/

I heard BOV are good but then i heard they are bad too.. Do they cause CEL or anything that could cause problems that aren't necessary at all?

[p0isin]

B7 A4 has a closed loop system. BOV is not recommended. A BOV allows air that has been metered by the maf to escape. This will cause a rich condition.

[oVeRdOsE]

All right.

- Stock 2.0T intake is already ''optimized'' for the 2.0 power. The filter is big enough for a decent pressure and speed drop. 2 intakes from the exterior air (one in the front and one in the fender)
- Let say pappy cars, such as nissan maxima with the 265hp v6 vq35de engine. Those ''luxury'' car are for comfort, so sound must be minimal. Intakes are not optimized for power. No surprise when you dyno the CAI and it gives you a steady 5-8 whp.

- Best option for sound 2.0 fsi sound :
-- Open cone air filter in the engine bay, with a proper heatshield that force the exterior air getting in by the OEM intakes (front and fender)
-- diverter valve spacer
-- tune to increase turbo output pressure
-- remove the hood ''foam'' liner (it's only clipped).

[UberTeile]

All right.

- Stock 2.0T intake is already ''optimized'' for the 2.0 power. The filter is big enough for a decent pressure and speed drop. 2 intakes from the exterior air (one in the front and one in the fender)
- Let say pappy cars, such as nissan maxima with the 265hp v6 vq35de engine. Those ''luxury'' car are for comfort, so sound must be minimal. Intakes are not optimized for power. No surprise when you dyno the CAI and it gives you a steady 5-8 whp.

- Best option for sound 2.0 fsi sound :
-- Open cone air filter in the engine bay, with a proper heatshield that force the exterior air getting in by the OEM intakes (front and fender)
-- diverter valve spacer
-- tune to increase turbo output pressure
-- remove the hood ''foam'' liner (it's only clipped).

Well said...let's put it to bed.[az]

[miA4]

I read a thread that this forum was dying. it may be due to the massive amount of dick swinging and kicking the new peoples dicks in when they ask a question. Yes yes yes, we know, SEARCH! I find a multitude of my info from google, not necessarily from Audizine. But damn, the guy asked a question, just answer it correctly or move along. simple solution to a dumb problem.

[Okedokey]

I read a thread that this forum was dying. it may be due to the massive amount of dick swinging and kicking the new peoples dicks in when they ask a question. Yes yes yes, we know, SEARCH! I find a multitude of my info from google, not necessarily from Audizine. But damn, the guy asked a question, just answer it correctly or move along. simple solution to a dumb problem.

Exactly.

[miA4]

Well said...let's put it to bed.[az]

you have to buy me dinner first.

[Okedokey]

What does removing the hood foam do? Dissipate heat better? Wouldn't that risk damaging paint?

[miA4]

What does removing the hood foam do? Dissipate heat better? Wouldn't that risk damaging paint?

the engine doesn't get that hot. I think it's just to quiet the noise coming from the engine.

[Okedokey]

the engine doesn't get that hot. I think it's just to quiet the noise coming from the engine.

So why would taking it off have anything to do with performance?

[1killera4]

All right.

- Stock 2.0T intake is already ''optimized'' for the 2.0 power. The filter is big enough for a decent pressure and speed drop. 2 intakes from the exterior air (one in the front and one in the fender)
- Let say pappy cars, such as nissan maxima with the 265hp v6 vq35de engine. Those ''luxury'' car are for comfort, so sound must be minimal. Intakes are not optimized for power. No surprise when you dyno the CAI and it gives you a steady 5-8 whp.

- Best option for sound 2.0 fsi sound :
-- Open cone air filter in the engine bay, with a proper heatshield that force the exterior air getting in by the OEM intakes (front and fender)
-- diverter valve spacer
-- tune to increase turbo output pressure
-- remove the hood ''foam'' liner (it's only clipped).

Corretomundo.

[Charles.waite]

I heard BOV are good but then i heard they are bad too.. Do they cause CEL or anything that could cause problems that aren't necessary at all?

Yes. They are bad. When you start dumping metered air into the atmosphere, the ECU has wrong calculations for how much air is being taken in by the engine at any given moment and you'll run rich and screw up the fuel adaptations and whatnot.

Yes it will still run but you're losing performance and efficiency simply for that whoosh sound.

[Charles.waite]

I read a thread that this forum was dying. it may be due to the massive amount of dick swinging and kicking the new peoples dicks in when they ask a question. Yes yes yes, we know, SEARCH! I find a multitude of my info from google, not necessarily from Audizine. But damn, the guy asked a question, just answer it correctly or move along. simple solution to a dumb problem.

People complain it's dying because people come in and ask questions that have been addressed a million times then get angry when we don't confirm that what they wanted to do isn't the correct step. We don't dislike custom intakes, they're simply not worth it from any perspective except for the noise the allow.

Some people don't like their ideas to get shot down, however right or wrong one might be...

But thanks for the education on how this forum should work. I'm clearly new here and needed to know how to Internet.

[Charles.waite]

the engine doesn't get that hot. I think it's just to quiet the noise coming from the engine.

It actually does. The catalyst is in the engine bay and it's gets around 700°C internally. Also the turbo gets really hot as well. Enough so that when you're driving hard it glows red hot. So while the engine block itself might not get that hot (which is relative, it's still hot enough to cause serious burns, and operating temps generally are at or above 90°C), other components in the engine bay really do generate a ton of heat.


So why would taking it off have anything to do with performance?

I think he was thinking it would allow more intake sound to come through when it's off.

My though about that cover was that it's for heat protection for the hood.

[Okedokey]

Mate, the sarcasm is really helpful. I agree with the poster above. Also I think he is referring to the immediate shut-downs from people. There isn't any patience. Sometimes people don't know what they don't know so a search engine isn't helpful. Secondly the audizine search function is woeful.


BTW, You keep claiming it wont make any difference however I showed MULTIPLE references showing you're wrong. Here is another http://www.audiworld.com/forums/a4-b7-platform-discussion-69/carbonio-intake-testing-review-b7-a4-2-0t-fsi-2670533/ this guy went from 201 g/s to 214 g/s simply by adding a CAI without the restrictions that the stock air box provides.

The point is, if you don't think it is value for money, that is fine, that's a personal choice, but it is simply not backed up by theoretical or real world data. A personal choice of 'value' isn't the same thing as 'effectiveness'. I agree, if I only had $1500 and had to choose a single mod, I wouldn't choose CAI, however some people don't have financial constraints and can choose all or none.

Lets see if this guy gets a proper answer? http://www.audizine.com/forum/showthread.php/677242-VAG-COM-Question

[Axis]

I'm clearly new here and needed to know how to Internet.

http://cdn.gagbay.com/2012/01/welcome_to_internet_ill_be_your_guide-20268.jpg

I can sell you the missing pixels in exchange of bitcoins.

[oVeRdOsE]

I read a thread that this forum was dying. it may be due to the massive amount of dick swinging and kicking the new peoples dicks in when they ask a question. Yes yes yes, we know, SEARCH! I find a multitude of my info from google, not necessarily from Audizine. But damn, the guy asked a question, just answer it correctly or move along. simple solution to a dumb problem.

Well that's my every day observation.

New generation does not get any interest in manual stuff. They can't do stuff by them-self. They are good in unique field, most of the time in what they work/study.
No surprise that there's no ''search reflex'' or ''forum dying''

You can see a massive car modification drop in many countries. massive meeting drop. And obviously a massive car forums inscription drop.
Massive increase of people who buy ''automatic'' stuff ( cars, appliance, electronics, software, etc).
Saying that iphone is the best device in the world, I have hard time to explain that this is NOT a magic box, even explaining how it works or giving the specs, it's a hard to most people to understand.

That's really sad, like I said, back in the days, you want to change your clutch, most of your neighbor can help you. Now it's hard to find someone in the whole city...

Rare to find a person with a office job, that can redone a 100% complete bathroom (elec, plomb, mec), changing a car clutch and doing a complex math calculation in the same time line.
which is my case. Luckily I make money because of ''incapable'' people, but sometimes you have to justify yourself because they don't know shit, and they can do a simply search or being logic...

* Note that I'm speaking generally from my everyday observation, I do not spoke about op, I don't know him.
I was just justifying the fact that '' the forums is dying''

Hard realization, even at my age.
And I'm mid-20, not 60.

[1killera4]

Some people don't like their ideas to get shot down, however right or wrong one might be...

But thanks for the education on how this forum should work. I'm clearly new here and needed to know how to Internet.

Muhahhahha...

[1killera4]

Well that's my every day observation.

New generation does not get any interest in manual stuff. They can't do stuff by them-self. They are good in unique field, most of the time in what they work/study.
No surprise that there's no ''search reflex'' or ''forum dying''

You can see a massive car modification drop in many countries. massive meeting drop. And obviously a massive car forums inscription drop.
Massive increase of people who buy ''automatic'' stuff ( cars, appliance, electronics, software, etc).
Saying that iphone is the best device in the world, I have hard time to explain that this is NOT a magic box, even explaining how it works or giving the specs, it's a hard to most people to understand.

That's really sad, like I said, back in the days, you want to change your clutch, most of your neighbor can help you. Now it's hard to find someone in the whole city...

Rare to find a person with a office job, that can redone a 100% complete bathroom (elec, plomb, mec), changing a car clutch and doing a complex math calculation in the same time line.
which is my case. Luckily I make money because of ''incapable'' people, but sometimes you have to justify yourself because they don't know shit, and they can do a simply search or being logic...

* Note that I'm speaking generally from my everyday observation, I do not spoke about op, I don't know him.
I was just justifying the fact that '' the forums is dying''

Hard realization, even at my age.
And I'm mid-20, not 60.I think you just exceeded my bandwidth. LOL

[miA4]

People complain it's dying because people come in and ask questions that have been addressed a million times then get angry when we don't confirm that what they wanted to do isn't the correct step. We don't dislike custom intakes, they're simply not worth it from any perspective except for the noise the allow.

Some people don't like their ideas to get shot down, however right or wrong one might be...

But thanks for the education on how this forum should work. I'm clearly new here and needed to know how to Internet.

your last comment leads me to believe that you take what I said personally. I understand that people don't like their ideas shot down or whatever. Clearly, you took something I said out of context, which is understandable on the internet. I just don't get the need for your last sentence. As the years go on, and this car gets cheaper to buy, people are going to come into this forum and write stupid shit. i'm 31 and have been working on cars since I was 16. regardless of whether you like it or not, you were this same exact person with dumb questions that pissed someone off at some point. Yes, that is how the forum should work. this is supposed to be a community of people helping each other out. I've never seen a forum where the senior members are always acting like they know everything and rather than helping out, they try to show how much of an ass they can be.

Problem: someone asked something stupid or that has been answered a million times.
Solution: click the back button....

[Okedokey]

^^ cannot agree more

[1killera4]

Does someone need a hug? [az]

[UberTeile]

you have to buy me dinner first.

You may have one item from the dollar menu @ McD's....and I'm not tucking you in afterwards. [:p]

[miA4]

You may have one item from the dollar menu @ McD's....and I AM tucking you in afterwards. [:p]

You can never go wrong with a McChicken sandwich. and I fixed that for you

[miA4]

Does someone need a hug? [az]

I don't know where Dunedin is.... But a virtual hug will do.

[Okedokey]

Ireland. ;)

[miA4]

Ireland. ;)
He's not that lucky. Dunedin is a city on the west coast of Florida. in which case he is lucky because he lives in florida and it's decent weather this time of year.

[Okedokey]

Yeah I saw FL. I was joking - :)

[1killera4]

yep..its beautiful here. 82 and sunny!

Have a great day all!

[BenMTL]

Pretty sure this thread was headed in the direction of "if I put a spectre foam filter directly onto my MAF will my car be super fast and go whoosh???"

NEED MOAR WHOOOOOOSH [drive]

[Charles.waite]

Mate, the sarcasm is really helpful. I agree with the poster above. Also I think he is referring to the immediate shut-downs from people. There isn't any patience. Sometimes people don't know what they don't know so a search engine isn't helpful. Secondly the audizine search function is woeful.


BTW, You keep claiming it wont make any difference however I showed MULTIPLE references showing you're wrong. Here is another http://www.audiworld.com/forums/a4-b7-platform-discussion-69/carbonio-intake-testing-review-b7-a4-2-0t-fsi-2670533/ this guy went from 201 g/s to 214 g/s simply by adding a CAI without the restrictions that the stock air box provides.

The point is, if you don't think it is value for money, that is fine, that's a personal choice, but it is simply not backed up by theoretical or real world data. A personal choice of 'value' isn't the same thing as 'effectiveness'. I agree, if I only had $1500 and had to choose a single mod, I wouldn't choose CAI, however some people don't have financial constraints and can choose all or none.

Lets see if this guy gets a proper answer? http://www.audizine.com/forum/showthread.php/677242-VAG-COM-Question

Actually it's been proven over and over and over again by b5/b6/b7/b8 guys over and over and over again that 99 times out of 100 a custom intake won't do much if anything outside of the margin of error for increasing power.

There is a guy (Bische) who swapped a 3.2 VR6 into his b6. Maybe you can use your search engine skills to find his thread. (That's sarcasm the link is right here: http://www.audizine.com/forum/showthread.php/417035-Bische-s-Wagon-The-thread/page43).

He's done some very rigorous testing pointing towards the stock air box not being a performance bottleneck up until fairly ludicrous numbers. And any test with a naturally aspirated engine doesn't apply to a turbocharged engine. As you surely know a turbo creates negative pressure in the intake and shoves air into the intake tract, thought about 4 rubber hoses, two intercoolers and a throttle body. The stock air box simply isn't a restriction and fucking around with it on a stock turbo car is pointless. Low single digit performance "increases" are generally within a margin of error, and honestly will not be at all noticeable in any sort of driving situation I can think of.

And for the record. I don't take this shit personally. I just find it tedious when people try to go down the CAI rabbit hole and try (ineffectually apparently) to nip it in the bud before too many noobs read the thread and thing sticking a cone filter onto their MAF will somehow make their car faster by ingesting super hot air from right next to the turbo and catalyst.

[Seerlah]

All you guys are going about this the wrong way. Click the link below for true performance. Well worth the price tag [;)]

http://www.ebay.com/itm/Stage-4-Aluminum-Electric-Electrical-Turbo-Turbocharger-Supercharger-Kit-12V-/181614222124?hash=item2a490d1b2c:g:-YgAAOSw7ThUj0US&vxp=mtr

[Charles.waite]

All you guys are going about this the wrong way. Click the link below for true performance. Well worth the price tag [;)]

http://www.ebay.com/itm/Stage-4-Aluminum-Electric-Electrical-Turbo-Turbocharger-Supercharger-Kit-12V-/181614222124?hash=item2a490d1b2c:g:-YgAAOSw7ThUj0US&vxp=mtr

Oh come on man! You're just part of the pro-OEM-hot-air-intake coalition here on Audizine. Get out of here!

[1killera4]

LOL

[Seerlah]

All i need is farts for my intake. Bag em up and send them my way. Adds to combustion. I have tests to prove it [:p]

[BenMTL]

All you guys are going about this the wrong way. Click the link below for true performance. Well worth the price tag [;)]

http://www.ebay.com/itm/Stage-4-Aluminum-Electric-Electrical-Turbo-Turbocharger-Supercharger-Kit-12V-/181614222124?hash=item2a490d1b2c:g:-YgAAOSw7ThUj0US&vxp=mtr


4 sold......[headbang] [facepalm]

[miA4]

4 sold......[headbang] [facepalm]

i'm in the wrong business.

[Seerlah]

He most likely bought them from himself, in an attempt to persuade potential buyers. Dude is living on another planet parallel to mine, thinking those will sell at that price. And sad enough, there is a reason he has them listed that high. Bait em and wait!

[tchuck]

This thread is bizarre.

[Seerlah]

That's because you dont know how to intake, bruh! Haha

[tchuck]

All you guys are going about this the wrong way....

I love the little boxes to highlight all the amazing features. Oh THAT'S where the aluminum alloy is.
.
http://images.tapatalk-cdn.com/15/11/12/4b2060cb747ec72cb708d24aaf83d32b.jpg

[Okedokey]

Actually it's been proven over and over and over again by b5/b6/b7/b8 guys over and over and over again that 99 times out of 100 a custom intake won't do much if anything outside of the margin of error for increasing power.

There is a guy (Bische) who swapped a 3.2 VR6 into his b6. Maybe you can use your search engine skills to find his thread. (That's sarcasm the link is right here: http://www.audizine.com/forum/showthread.php/417035-Bische-s-Wagon-The-thread/page43).

He's done some very rigorous testing pointing towards the stock air box not being a performance bottleneck up until fairly ludicrous numbers. And any test with a naturally aspirated engine doesn't apply to a turbocharged engine. As you surely know a turbo creates negative pressure in the intake and shoves air into the intake tract, thought about 4 rubber hoses, two intercoolers and a throttle body. The stock air box simply isn't a restriction and fucking around with it on a stock turbo car is pointless. Low single digit performance "increases" are generally within a margin of error, and honestly will not be at all noticeable in any sort of driving situation I can think of.

And for the record. I don't take this shit personally. I just find it tedious when people try to go down the CAI rabbit hole and try (ineffectually apparently) to nip it in the bud before too many noobs read the thread and thing sticking a cone filter onto their MAF will somehow make their car faster by ingesting super hot air from right next to the turbo and catalyst.

LOL