abhi, does your friend have a Full Exhaust or a bolt on??! If you have a full exhaust I recomend that you tune it up on a dyno... Thats the right way to do it and that the safe way to do it. I would recomend the PCIII compared to PCII, I havent installed mine yet... but thats the general opinion I got from a lot of people. The K&N exhaust is a good add-on, but if you want it to show any performance differences... then you are knowing the wrong door. Its a nice filter, and it will last you the life time of the bike, and you need to clean it lot less... but thats where the benifits end.