There's various opinions on this. It depends on your budget.
If you're strapped and you NEED to replace the filter, go with the drop in.
If you can spare $200 and need to replace the filter, by all means, get the K&N CAI.
If money is no object, go get that thing regardless of the current filter.
Some previous observations:
The K&N FIPK's heat shield doesn't do much unless you insulate the top and the sides with some kind of PVC foam.
A member showed us EFILive readings of two 30 minute drives. The first, with just the CAI, showed 145-150 degree IATs, whereas the second, with PVC foam insulation, showed 90 degree IATs.
Some have even reported success (but no sensor readings) with modifying the stock airbox to fit over the K&N CAI.
Hope this helps. MY opinion is that I would get the CAI as soon as I needed a new filter.
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