ok my take on K&N filter. Am not an engineer or a technical person but just my observations. If it a free flow filter, it allows more air to pass through it. Also this means more particulate matter.
I did a small test- I held a normal cotton filter and the K&N stock filter against a tube-light. I was able to see the pores through the K&N but not in the normal filter. So it is definitely more porous. Btw
i am using stock replacement filter in my Alto 800cc and it definitely has increased the power upfront. Is it causing any engine damage? frankly I don't know. Hope not
Am not sure if it is worth spending 3k. But a conical air filter with good plumbing work which actually draws in cold air and not the warmed up air under the hood should be fine. Read good plumbing! Thats the most imp thing.
@amiti- U can try a stock replacement to begin with. If u r not happy then switch back to normal filter.