Alot on here would say to stick with the stock filter system. It is a very good system indeed.
But if you choose to go aftermarket, make sure you get something that filters out as much of the nasty stuff as possible.
Alot would also say not to go with the K&N filter for the 6.0. It lets way too much stuff thru and it could possibly do damage to the turbo.
I am not an expert of any of these, just passing along the same info that I have seen others post about.
I decided to go with the Banks ram-air filter intake system. It has an 8 media filter, which is cleanable and re-usable. It also has a cover over the filter to keep the HOT engine heat out. You want COOL air coming in.
Others have also gone with the AFE stage II system. It and the Banks are about the same money.
My advise would be to do alot of research on all available systems and make your decision based on all the info you can find.
Happy Hunting.
Pic before install
Pic after install