Main difference between K&N and Green Cotton filters is that green cotton do not need oil when being serviced where as the K&N's do.You can say green cottons are a little more better (dont know why , but that's what majority of people say)
Green Cotton Stock replacement (if available) will cost you rs 4500.
Green Cotton Storm ( performance oriented) will cost you around rs 6000.
does these filters arises any adverse effects to engines? as i can imagine they will alter compression ratio and such things any chances of blowing the turbo or bricking up the engine?
There are no adverse effects as such with any kind of performance filters unless its branded & been put by someone who knows what he is doing.
Compression ratios cant be altered unless you open up the engine.
If the filter is installed properly it wont cause any probs to the turbo or your engine.