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.
Chris