Just checked my air cleaner since I just bought the truck. It needs replaced. Anyway, I've used K&N's before in my Fords, Toyotas, and on my Harley. Would my 5.9 honestly gain anything from it, or should I just get a stock replacement???? Thanks.....

 

It depends on what type of results you are looking for. K & N is going to give you a louder sound and improved throttle response. Most people, (myself included) buy aftermarket equipment for improved vehicle performance. If performance is not of concern for you then you might as well stick with the stock filter. I can tell you this however; I have K&N's FIPK kit on my truck, and I think it was worth it.

 

On a 5.9L, you should see a difference. Welcome to DF.