Posted by
rohit.b.d. Well, its not an improvment in performance - just that the engine is now getting relatively a bit more air for the same amount of the accelerator push, causing it to respond better to the throttle.
Well, that is what I, and almost everybody calls performance improvement, Rohit! 
but this is just to needle you, Rohit, before I say K&N are not really all that better than the stock filter (or no filter at all), for flow improvement. (check the bob the oil guy link below)
Posted by
rohit.b.d.
The same can be replicated by simply changing the stock filter with a new OEM filter. With free-flow filters of the same size as OEM, all we're doing is allowing less obstruction (and resulting less filtering) to air.
If you really want good filtering and less obstruction its better to go for a larger air filter OF THE SAME filtering mesh size as the original stock one - fitting it in is a different matter, though - and in Manjunath's case the conical filter probably does have a greater surface area to let in more air.
OEM = Original Equipment Manufacturer = STOCK.
Rohit's second paragraph quoted above makes sense, from theoretical point of view.
However, overall, I don't recommend K&N filters to anyone, because of the scathing reviews from filter performance analysis found online on the internet. Bob the oil guy literally tears K&N filters apart, accusing them of low FILTERING performance, with solid proof. Either ways, the flow improvements are nothing to crow about, and one is better off without the fancypants filters and the associated expenses.
For best filtering results and longevity of the engine, better stick to the filter the car came with.
