K&N Air filters sure drive a lot of people nuts.
Some people have excellent results with them. Over-oiling, over cleaning, seems to be the biggest problem. I put a drop in at 20k or so. l may clean it at 50k. I pull the air hose off with each oil change, easier to get to the filter. Turbo never shows any sign of dirt or oil. It's been to the dealer for various warranty, never any question or issue.
I am mostly stock. I like the OEM filter housing, as it draws air from the front of the truck through the fender. Seems like a decent design to me. Ido put grease on the edges of the filter to assuer a good seal. This is proabaly a good practice even with the stock filter.
I have a Vulcan big line kit. I had work done to the fuel tank as it was leaking. No problem, no question.
I think it just depends on the dealer. I have been VERY happy with mine. I did not buy the truck there, either.

 

Mopar can not void warranty based on aftermarket devices unless it affect emissions or proper operation, which they would have to prove cause the failure, or they add have to add claus to there warranty contract that states "any aftermarket modification not mopar approved will void the warranty" this is all per a friend of mine, whom is a lawyer who does this "it is or isnt warrantied"

 

Why do you think you would need to change the air filter every month? I put 22K on the factory air filter and it was still good when I replaced it but I did so just because it was 2 years old. Unless you drive mostly on dirt or gravel roads an good air filter should last 20-30,000 miles.

JMHO