let me tell you about my experience with K&N Filters
i got it fixed on my Yamaha Rx 135(2002-KA05 EJ147), 3mm ported bore at Power crest, Bangalore next to choudaiah memorial hall Malleshwaram.
let me just ask you guys one question , do you think K&N would still be in buisness if they charge ~200 to a new filter & people get zero performance improvement ?????(cost, including a flange Rs3600/-)
The day i got K&N filter on my bike even i was pissed off, since there was not much change in engine performance, but after 500 kms(the oil in the filter needs to get adjusted), the torgue is simply amazing, i used to get a mileage of 23kmpl (b'cas of porting) in city limits & now it is a whooping 30kmpl & i touch nearly 80 to 90 kms within city limits(near south end , nanda theatre double road). topend has now drastically improved to 110 -115kms( with catalytic it is touch to even touch 100km).
what more do u ask, if u need first hand info , u can always test ride my bike & get in touch with me at [email protected]
i am planning to get a K&N tycoon intake filter on my car at a cost >14K

thanks guys