K&N filter success is a very nice example of a sucessfull marketing campain. They sponsor lots of HighPerformance events, are present in almost all car magazines and conduct a very high profile advertizing. BUT:
Many have reported MAFS problems as oil from the filter is sucked in and coats the MAFS
My personnal experience with K&N. A few years ago, at Moroso Race Park Fl, K&N had a display where they had installed a dynamometer for testing before/after K&N" I was there with my 1978 Vette, 383cu.in, ''reasonnably'' fed with some ''steroids''. I had a regular paper filter on the car. The rep. convinced me to go on the dynamometer for a comparative run. They had previously done several runs with other cars where HP gains were fairly impressive. However, he stongly insisted that HE runs the car, for ''security reasons''. I said..no way. I run the car. After a bit of arguement, he allowed me to run it.
First pass: 362HP @ 5,800RPM. (regular paper filter)
Second pass: 358HP @ 5850RPM, (with the K&N)
Agreed, the difference is very small and probably due to outside factors or normal variations. But my results were far from the results they were getting with the K@N driver where constant improvement of 10% to 15% were recorded with other cars. Driver tricks??? probably. most likely
Keep your hard earned money and buy a set of new spark plugs. You'll get better result with those.