If you ask 10 different people you'll get 10 different answers. I have an AFE drop-in filter in the stock box. There's dozens of threads about them. Do a search and go from there.
I've used K&N products on every vehicle I've owned except the Tundra with no problems. K&N won't mess your truck up. People that don't know how to clean and oil them properly mess stuff up whether it's K&N, Airaid, or any of the other oiled filters.Volant is really good, I use it. I'd stay away from K&n, there is sum threads that say how they can mess up your truck.
I plan on keeping the stock setup with the drop-in. The only other thing I have considered is getting the Airaid Jr. kit to try out the tube from the airbox to throttle body. It looks like it MAY provide an improvement.I had K&N FIPK, K&N Drop in, Volant intake, & stock intake.
K&N drop in: not a dang thing in any category.
K&N FIPK: made my dual exhaust sound really throaty, Loss of low end torque, no MPG increase.
Volant intake: not as loud as the Volant, Felt very little loss in low end torque, Very impressed in the HP gain. I was spinning tires on dry pavement. MPG NA: Only put 20 miles on it and then sold it.
Stock intake: run the stock filter and call it a day.
If I didn't need the money at the time when I sold the Volant intake, I would have kept it. I was very impressed with it.
But I'm back to running the stock intake and it serves its purpose quite well I think.