My dealer told me that a K&N filter upgrade will give a noticeable performance boost to my 400i auto. Has anyone added one and seen any great benefit? Also, is there a good online source for these at a good price?

 

I have put K&Ns on 2 atvs I owned. I could not tell a "noticeable" power boost at all. If you order one get the prefilter also. K&Ns do not stop the dirt as well as a factory foam filter but do a better job at repelling water if you get water in the box.

After having bought 2, I would not waste the money on another one.

 

My dealer told me that it would make a little difference, but he does not reccommend them. He said that the boost power by letting more air in, but he said it also lets larger dirt particles through, which is worse than a little loss of power for a stock filter.

 

Hence the prefilter. I personally use a uni, for the simple reason that i mud a lot. And the dust protection should be comparable to kn w/prefilter. and its half the price.

 

I would have to agree guys i run the twin air filter. Didn't notice a big difference but i did notice a small difference, also it protects better than a k&n.