I have used K&N filters for many years on my cars but this test has given me cause for thought
K&N Air Filter Review - Debunking the Myths (and why OEM is better)
A search of the net will show that the test was faulty to some degree but still there are plusses and minuses with each filter type and it depends on the environment you drive in (very dusty or not) the life you expect from your engine 50 000 miles or 150 000 miles and how important those extra 15 hp are when making your choice - just make sure that choice is well informed