HielToh

I was talking to my mechanic, Terry Griffin in Berkeley, CA - very knowledgable guy, who told me that I ought to get my K&N out of my turbocharged engine ASAP b/c the high-flow design actually lets a dangerous amount of particulate matter into the turbo's compressor (not to mention the rest of the intake track and the cylinders). He recommended either going back to - god forbid - a factory-style paper filter as long as it was European manufactured (Mann or Mahle were the names he gave), or if I wanted to stick with a non-paper, reusable and high-flowing filter, to buy a RamAir filter(made in the U.K.) If you're using a K&N in a 1.8T, or some.other T, take it out and look through it - you'll be able to see Shamu, or that guy from the eating contest, or even an Excursion, through any one of the "hi-flow" holes.

MattKA4

ummm yeah ok....thats why APR recomends them

Maccorrado-SNA/DTW

local mechanic or APR....i'd um, have to side with APR on this one

[ej257]

everybody has an opinion...some are right.

Ray Khan

I don't think they would do this if they felt it put the turbos life in danger.

Chard

in the Bay Area. I don't necessarily agree with what's being said here, just wanted to let you know that.

paul_858

doing a worse job at filtering.

Audi2ptzero

Maybe he has something against K&N the company.

paul_858

"supported" by APR doesn't mean it's true. Just wanted to make sure you understand that.

Same goes for GIAC/Wetterauer/O.CT/MTM/ABT etc etc

VicG

I'll preface this by saying I've run K&N filters on my race motorcycles for many years. They are great filters when the application warrents their use.

As far as using one on a stock A4:

1. The paper filter on a stock engine flows enough air through the complete rpm range that makes it not necessary in my stock engine application. I cannot say this applies to the high flow turbo change-outs, as I have not worked on any of that stuff.

2. I'm concerned about the oil in the intake tract hosing up the MAF. Most users don't know the correct way to oil these filters, they put way too much oil on and cause this problem to happen.

3. Although there can be cost savings using K&N filters, they have a "sweet spot" where they pass more "larger" particles early during the install (K&N says that they actually work better when "dirty"), they can actually flow less air when really dirty. Take off your K&N and check it out after those "tree fuzzies" happen in late spring, you'll see what I mean... So bottom line, they require regular maintenance. More than just taking out the paper thing and tossing it once-in-a-while.

4. There is debate whether these filters let thru "harmful" particle sizes (dirt). If I lived in a place like Arizona, I'd be concerned with potential abrasive material getting thru. Otherwise, it's not a concern in a regular environment.

Bottom line if you want to run one, that's fine. Just sharing some of the stuff I've experienced with them.

Best,
Vic