depends.....if you are leaving the stock bottom half of the airbox or not. The interior of the airbox is about 13" x 5". So, your filter would need to have no more than a 5" diameter on either end to fit into it. If you take the airbox completely out it really is not going to matter what size your filter is because just about anything will fit.
Also, the elbow would need to be a reducer......in other words 2.75" on one side and 3" on the other. The MAF is 70mm / 2.75" and you want a good tight fitment that wont blow/fall off. Same goes for the other end of the elbow, you would want to use a 3" coupler pipe between the filter and the elbow so that your fitment is good and tight there as well.

 

i have 130 miles on my S i just got it friday how long should i wait til i change stock to my kn rx-4990?

 

I dont see any reason to wait at all. I did mine in the first few days I had the car.

 

thanks for the quick response how do i switch i did this to my 03 cooper (i bought a new filter for my s of course) but i dont think it had a air flow sensor im probably wrong

 

You can do one of two things:

1. just undo the two screws that hold the intake pipe to the air box, and affix the filter straight to the MAF itself

2. undo the screws, and remove the airbox completely. then affix a 90 deg elbow to the MAF and then use a coupler to join the filter to the elbow

The second opption is believed the best way to go since the elbow allows the airflow to match that of the stock setup.

I can tell you from experience that the elbow option does work best and is much quieter between shifts when the by-pass valve releases.

 

any way to remove the platic air scoop gaurd? i removed the two phillips screws but cant seeem to get it out

 

there is a screw underneath a black rubber cap on the underside. instructions further back in the thread

 

did this mod tonight. thing is SUPER LOUD. gonna do what i can to quiet it up a bit.

 

Those of you with K&N filters on your car (for at least a few weeks), remove the filter/tubing mounted on the MAF, run your clean finger across the grating, and tell me what you see...?

I got a dark oily layer of goo. And it was not there before the K&N install.
Also, there was a bunch oily residue on the black "manifold" just below where the filter sits.

All that talk from K&N saying no oil gets on the MAF is BS....I think. I got proof.

 

thanks for the response...sorry couldn't answer quicker i was at work(24hrs).... i bought that 90 deg. elbow(3"to2.75") and 3" coupling that you posted and i'm now in debate between the 9" AEM dryflow filter with the 3" opening or the 5" AEM dryflow filter with the 3" opening...any ideas? i'm planning on keeping the bottom half of the stock box in place...thanks

 

That's exactly what I am considering (...and the reason I took off my filter was to install the bottom half of the box). Supposedly the AEM has slightly more restricted flow due to better filtering...so I am thinking the 9" long filter will compensate for that...and it should fit.

And here is a very well done filter test that I found, comparing K&N, paper, etc:
http://www.bobistheoilguy.com/airfilter/airtest1.htm

...hence, I'm not liking K&N so much.

 

Sorry..so your gonna keep the bottom of the box?
-i see now the reason you found the oil....yeah i'm not even considering k&n...AEM dryflow is my only choice, but don't know if the 9" will fit with the bottom of the box.....

 

Yeah, I plan to keep the bottom of the airbox. I'm pretty sure the AEM filter will fit...the OD of the filter is same as the K&N and it tapers down too, it's just a bit longer. {this is what I'm looking at: http://www.aempower.com/ViewProduct.aspx?ProductID=320 }

 

Thats the same filter i'm looking to buy i just couldn't find the O.D. of it at its widest part...but i guess you can be right.. its the same O.D. just longer??

 

My hood scoop came from the factory with every other column on the black mess insert already opened, so is that good enough or should I remove the entire insert?

 

i removed everything

 

I removed everything, and painted the metal behind the scoop satin black......looks very good, like it came from the factory that way.

 

well i just ordered the AEM dryflow 9" filter...should be coming on Monday...so till then i'll just have to wait...i'll keep u guys posted on fitment and such. As for the scoop mod...it rains a lot here in Miami so don't know if i want to take if off...any ideas.. should i just open up more holes than the factory one that are already open..?

 

I live in the rainy northwest, and have no problem with the scoop insert removed. I have a 20 mile trip to work, and it rained the whole way today. I popped the hood and it was bone dry under there. i believe most of the rain water hits that bit of metal located just behind where the insert sits, and the drains out through drain holes in the bottome front part of the hood.

 

when did they start doing that??? Mine is solid

 

I ordered my car the 3rd of Feb, and it came with the slightly open scoop.

 

Replaced my scoop with a grate, homemade, and poppd on this!

http://www.imgshost.com/uploads/d309559cee.jpg

 

Sorry already took it off Not sure if the mod was a direct change in MPG, or if I just reved more to hear my PSSST! sound, either way after driving for about a week and a half (one tank) driving to wrok, friends etc, 30% highway, 70% street I was getting 22.4mpg solid... Now~

Once I went back to stock, I really felt that firm solid push, The main reason I love the car, so Sorry, but I'm going back to stock for now, also after half a tank so far I've gotten 27mpg... I cannot say whether its the feeling, or if it is actually the mod or maybe a bit of both!

Top speed I don't actually see much difference, I did not officially time it or compare to another mini, not allot around, but I felt a difference for the better for stock, and a difference for the worse for the "upgrade" I will say it really is cool to hear the BoV but it is too costly for now, perhaps I'll get an alta if I miss it enough!

as a note: When you are climbing speeds, then letting off and climbing again, with the mod you feel a power loss, and then the car has to almost struggle to get air back in, while with stock, you slowly drop down, and then when you ask for the power back, it is almost instant, this may just be me being crazy, but I think it is true.

Just my 2 cents!

 

i think we will have to agree to disagree. i put my stock airbox on to compare as well and while it started off the line a bit better it didnt pull nearly as hard in the mid to upper RPMs especially the top end of the spectrum. MPG may be a bit better with the stock box but i bet that is in your head more than you would think. with the short ram you can hear yourself when you really get on it and when you shift or let off the accelerator, so i bet you are more likley to push it harder than you would on the stock box.
2 more pennies in the jar

 

I give up, put the short ram back on, it sounds so much cooler *sigh* -- im almost positive its my driving because I was pushing it to work, to see how the mpg compared, I duno whatever! leave me alone, mods rule! PSSST!!!11