The filter is only a very fine cotton mesh held in by the wire grid so don't ever try to dry or clean them with an air compressor as it will just either blow holes in the filter or separate the knitting in the cotton.
My father in-law did this for me years ago and being old (hard of hearing and seeing) he damaged a few areas on the filter.
Not a big problem but still I'd advise against it...
As far as gains on the stock filter vs K&N filter types and even no filter debate it's been proven time and time again that they work and work well so if there is someone out there who owns there own shop with dyno you better head to the nearest bottle-o...
I have swapped and changed on the fly while on the dyno with my old tuner (2005-6) and xr6t's and my own supercharged ba xr8.
Check the
AFR's when doing it this...
Push 20-40psi through a stock filter then change it over for K&N or even the foam filter style and see the
AFR's!
Anyway...For such a small outlay and something that never needs replacing or cleaning for that matter unless you live in dust it's a no brainer and plus majority of people rarely keep the standard intake setup so an aftermarket item is needed.
Here is a youtube video of the Mighty Car Mod blokes (excellent stuff) which disproves my above info but hey there are many factors-
https://www.youtube.com/watch?v=PAIxeQUSg-Q
Also on a different note, watch this one also which is just wow-
https://www.youtube.com/watch?v=f1QL9veQaNg
Something about once you go black...Haha