Which aftermarket filter is better? I'm thinking about putting one on my Scrambler 400. Will I have to re-jet, it seems pretty rich from the factory. The throttle response could use an improvement.

 

Do what i did buy a kn and a foam filter i bought a twin air one. You shouldnt have to rejet

 

I forgot to tell you why i bought to of them the kn dont stop as much fine dirt. so when its really dusty put the twin air or uni on.

 

I can't give a first hand opinion on the K&N. What I have been told and read is that the K&N will let fine dust particles pass thru. I have a UNI installed in my EX. UNI - high flow and does not let fine dust particles in. Plus the guy at UNI e-mailed me saying that the UNI would flow more air than my ride would need fully modified! How can you beat that! They also recommend that the main jet size be upped 2 sizes. I still have the E-mail if anyone wants to see it. Hope this helps!

 

I use a K&N and a Uni on my 99 Sport. They are both great filters, and I haven't had a problem with either. Keep them clean and oiled. You will notice a lot peppier throttle response with both.