Is it a good idea to change the stock air filter to a K & N filter, what are the good or bad. Do i actually need to changethe full intake or i can just change the filter
will it loss power or use more gas?

 

OMG dont do it unless you want your check engine light to come on. I just had a couple of threads on this in A4 area. They do add a little bit but or power but they have are oily and they oil will come on to your Mass air flow sensor and put on your check engine light. so just dont do it get a dry filter. When i get home i am cleaning my MAF.

 

I dunno man, I got an s4 with the K&N filter. Nothing bads happened so far, check engine light isn't on, and theres nothing leaking onto the MAF. Maybe theres a difference between those and the ones in the A4's
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if the filter is too oily and a glob of oil gets on your MAF sensor, then yea that will cause your car to act funky because the MAF measures temperature and calculates air flow.. so if its oily it would not lose temp as fast... but mostly its fine just make sure the filter isnt drenched in oil...

other than that though.. i used to like K&N filters for the flow.. but found out that bits of dirt can actually make it through, the gaps are huge.. hold it up to the light.

 

65K miles on my K&N with ZERO problems

 

Ashred of evidenceon thissubject...
Ihave recently purchasedan '01 s4and ittoohas the check engine light on. The dealer said they checked it and told meit was a sensor in the torque converter. (They even bought a new t.c. for me and said they will replace it as this is the only way to change the sensor!) Anyways, I went to get the oil changedthe other day and found that ithas a K&N air filter replacement (no intake mods). Of courseI thought nothing of it until now. --Score--: K&N air filter problems = 2; K&N air filter no problems = 1.
--makes ya wonder, huh?I am notwith my car at the moment but as soon asI get homeI am going toget the codes checked for the check enginelight andseewhat it says.(Just a quick reminder for ya'll out there,Dealers might be wrong!!!<--go figure)
I will let you know whatI find with the codes and maybeI will end up changing out the air filter (was gonna put in an intake anyways, just not right away.)
ONE QUESTION; Does anyone know if I will now need to replace the MAF; if that ends up being the problem?-- now accepting all legitimate, knowledgeable, proven masters of this subjects responsesbelow...
Peace~

 

Do it! K&N makes great filters. no codes thrown here.

 

BMC filter. if oil from your high flow filter is getting downstream , you are using WAY TOO MUCH.

 

any good intakes for these then? b5 s4

 

I have the k&N and no problems, everyonce and a while i spray down the MAF with MAF sensor just ot be safe