I run a drop in and I really don't see a difference. I'm sure there is a minor performancxe advantage and maybe a mpg or two better. I'm sure the FIPK kit would be more effectove.
If you have not already done so, use the "Search" function and type in "K&N Air Filter". Then you will be able to read through numerous posts some of which might give you more information.
I have a K&N Drop-in and it works fine. Between the TRD, Trueflow, K&N, and whatever other drop in aftermarket filter you might find, just go with the one you can get the cheapest because, let's be honest, there really isn't any difference...