ok i just got my ex and i was wondering whats the best/good aftermarket air filter for it, if I get a K&N and the dust cover for it will it make a big gain in the power if i take off the airbox lid? or will it be a bad Idea??? thanxs

K&N is the way to go.... i run a K&N with a precharger, and my lid off... most of the time.. but when it's muddy out.. or if i go to trails i take my airbox lid (i have a large rectuangular hole cut out with a screen over it)

just remember if you take you lid off or put holes in it you have to rejet your carb

Keep the stock air filter. The K&N is a good air filter, but if you ride in heavey dust it will not trap all of the fine dirt. Read the fine print on the box about riding in heavy dust. It does flow more air than a foam filter, but when you put the outerwears cover on it cut it down to the flow of a foam filter. We used to run on our R's K&N for many years but this winter after talking to some people we have changed to foam filters.
Compare the stock filter to a Twin Air and they are about the same. So stay with the stock filter . Do run a outerwears cover on it to help.

thanks for the info... but does the K&n with the outerwear have the same protection as a stock foam filter without an outerwear?

A K&N filter with its sock (precharger) should give better performance than a foam filter by itself. I myself simply rejet my carb (its easy) when needed instead of cutting a hole or removing my air box lid. Different strokes for different folks.

ummmmm i put a K&N and outerwears on my quad and it flows ALOT more air and gave it a good boost in power for the money alot better than foam ALWAYS gonna go with K&Ns for now on

UNIFILTER is the only way to go if you trailride.Theres my 2 cents added into the pot.

well i'm gonna go with a K$N with a pre-charger, well since its gonna come from the fourwheeler i'm gettin. thanxs