To increase power the most you want something with a plastic tube.
The oil -vs- no oil filter really is a way over blown issue. If you go oiled just buy a prefilter through the company or through outterwear. You do that and you'll only clean oil the thing once in 50k miles. And then just simply make it pink. Not red. AND THEN if you do over oil it all it takes is a $4 can of electrical contact cleaner and spraying down the sensor. You don't even touch it.. believe me. This issue has blow 100 times out of proportition.
For what it's worth, check out my post on installing the K&N kit. I graphed before and after power levels.
He who is enslaved to the compass is free to sail the seas