I saw a couple of references to K&N Filters being bad in other threads.
I replaced the regular air filter with a K&N filter, is that not a good idea?

 

The K&N's let a little to much dust through for the turbo.

 

Once restricted the K&N have a bad habit of sucking in and allowing dirt to bypass into the engine. This is partially due to the poor design of the factory air box.

 

Should I put a standard filter back in or is it worth it to upgrade the air box?

 

If you want it quiet and clean the AIS upgrade is well worth it. Much better filtration than almost anything.

 

Upgrade the air box, let that engine breath better. Ford AIS, Tymar, and AFE stage II are some popular upgrades that have proven to work for many folks on this & other sites.

 

I agree 100% and if your truck is modified with a chip, consider adding a foam fender sleeve to maximize air to the filter.

 

I'm another vote for the AIS. Put one in mine cause the stock air box was letting dust in. One of the shops had a great price on them.

 

I have an airaid air system in my 2001 psd is that as bad as the k&n filter? will it let dirt bypass into the engine? What do you guys think about the airaid filters?

 

If your looking for something on the cheaper side go with the 6637 mod for $30 in filter and parts you can open up the intake and get better filtration than the stock airbox

 

AFE stage 2 with proguard 7 filter...i love it..makes the turbo sing...have a big hill out front of the house..climb it at 50 with a K&N box and stock exhaust..added the AFE and my 5" strait pipe and climb the same hill at 57...added the dp tuner put in 80 econo and now climb it at 96 and run out of room..

 

What about the 6637 filter or Kwik filter as some call it ?? How do you think it compares with the AIS of something like a K&N ??

 

Well I found the AFE Stage 2 on Ebay for 340, so I bought it and it is on the way. Cant wait to install it!

I think the muffler is coming off next, how loud is it without the muffler with stock exhaust?

 

I dunno, personally, I think any red colored filter paper is ultimately made by the same company and rebranded to whoever they have contracts with (ie: K&N, S&B, AEM, Airraid, etc.)

I used to be a red filter guy with all of my gasoline engines. I did notice that most of my engines with red filters start to burn more oil. From my Honda Civic to my Ford Expedition. They all started to burn more oil with the K&N style red filters. I will not use anything other than OEM brand filters, Wix or Fleetguard (cummins filtration) filters. Brands that do not release nominal micron ratings or flow specs don't get my business. Fleetguard (now cummins filtration) or WIX tech support will give you all the information you need when inquiring about nominal micron ratings and/or flow specs. It is very hard to find any other company that will even disclose some of this info. Even Racor brand doesn't disclose this info. It is also hard to find a filter that will flow lots of air w/o compromising filtration. Fleetguard is the only company that can show me that.

 

I bought an AIS based on what I read here, and the advice of a friend. This friend has been a Ford mechanic for 25+ years and told me about a training class he went to in Denver just after the AIS was released. The instructor had a 2000 7.3 PSD auto and put and test the K&N panel filter, AFE, and others, along with the AIS. Fresh oil change before changing intakes. He did an oil analysis after running each setup and the AIS had the cleanest results by far. All others allowed more air, and felt "crisper", but the oil was much dirtier, which would lead to more wear on internal parts. For my money, you can't beat the AIS. I just added the foam fender sleeve this weekend so we'll see if that does anything noticeable.

Was the 'test' official? NO. Just a real-world diesel mechanic testing equipment in real-world conditions so that he would know what he was talking about, and not spewing back the marketing mumbo-jumbo.