You'll get a lot of opinions.
Maybe gain a hp or 2.
There's been a rumor floating around for years that you can lose a hp or 2 with an aftermarket filter...yet no one ever posts dyno results to prove it. And last time I checked, more air in and more air out, tuned, means more power(even if it is just a little).
So, before anyone else brings it up, bring your dyno proof with you.
I had the K&N, and later a BMC race in my gen2(BMC Race was about 2/3 as thick as the K&N). You can hear the difference from under the tank immediately, so the engine is able to breathe easier. The off idle throttle response felt better than stock too.
Best thing though is that they are reusable.
Well the dyno sheets were provided by a member that ran a shop, but they're dated now. The Gen II hadn't been released and over the past 6 years things might have changed.
I'm running the factory filter in my '08. My understanding is that race filters flow more air, but they also allow more dirt to flow through your engine. If you're a daily rider I would suggest you stick with the OEM.
Opinions, Elbows and butholes....
Well, that's still early my friend, and I didn't say after market filters , I said race filters. I'm not as good as you on maintenance. Over 40K and only one filter change. As a matter of fact I've got 20K miles on the current set of plugs :shutup:ooooops........36,000 miles of daily riding later. I have not had a single issue, then again I am meticilous when it comes to cleaning and re-oiling the filter.
Supposedly,depending on who's azzhole...I mean who's opinon you wanna trust,a K&N or BMC will actually improve it's filtering capabilities as time goes by. Meaning the dirtier it gets,the more dirt will stick to it. I agree with the chef ^ somewhat. The most common mistakes made with a re-useable air filter is that people clean them too often,they use compressed air on them,they use harsh chemicals,and they over or under oil them. Remember that these filters are generally made of thin cotton.