I run the K&N replacement filter in my 05 Hemi and I like it.I ran the truck for the 1st time at the local track and I was running .20 faster then another Hemi Ram,not sure if that was what made the difference or not? If you do buy one remember to disconnect the battery to reteach computor to the new air flow.
The air flow debate is one that will carry on long past our imaginations K&N filters are not cheap...Mind you it is an air filter they claim HIGH air flow .To properly filter air it must come in contact with media.(filter material)..K&N uses a lite type oil to trap dirt in the media they use..it is less media then you would find in a conventional filter...so as science has it i would say its less protected....K&N =$$$...Nosie....and more $$$ to maitain it...Stick with an OEM replacement...also a slighty dirty airfilter protects better thena new one but doesnt mean neglete it
If you are referring to a drop-in filter, they are "worth the money" if you keep the vehicle for, say, 100,000 miles. The fact that the K&N is re-usable means you don't have to keep buying paper disposable filters ever 10 or 20k. Don't expect a major (or even minor) performance increase, tho. I did a K&N drop-in on my '97 F-150 and the difference was very minimal (if at all). You need to do a CAI setup for a noticeable difference. Stock intakes are restrictive by nature (mostly to produce a generic torque curve and to reduce intake noise), and changing the filter element alone will accomplish little.
Try this: take your stock filter out and go for a rip around the block. Feel any difference?
Didn't think so.
But having said all that, I'm shopping for a deal on a K&N filter for the wife's ride...(Which we plan to keep for a long time!)