This is kind of a rant... I installed a K&N filter on my air aid intake system because the old filter was warn out and the k&N filter was much cheaper then the replacement air aid filter. Keep in mind ive had the K&N filter on the truck for about 1 year it was a washable filter. I took good care of cleaning and oiling the filter. Last week i cleaned out the filter with a pressure washer and i noticed Holes EVERYWHERE in the filter. I then checked my compressor wheel on the turbo it was covered in fine dust and oil from the ccv. Needless to say i am no longer a K&N fan... So i went ahead and did the ccv mod and the 6637 mod. I am very pleased with this filter set up. I have been chasing around turbo fluttering problems changed all my IC boots and leak checked the system and after changing to the 6637 my next purchase was going to be a ported housing. But the 6637 eliminated the compressor surge. It did a few things too my engine sounds quieter for some reason it runs a heck of a lot better and what i found odd is that it seems to shift a little better too. (Not sure how). Anyway just thought i would share my experience. I'm not sure if i posted this in the proper section sorry.