stock air filter vs. Uni?

[HondaChris]

On a 2002 400EX, whats the difference between the foam stock air filter, and a foam Uni? I was told by more than one, that Uni is the OEM manufacturer for this...if its the same material, why would I need to buy a Uni for an improvement? And why we're on air filters, I have also been told that a smaller than stock filter is better, to create "less dead air space" around the filter for better air flow, and told by another that bigger than stock is better, to create more air flow...who is correct on this?

[remlapr]

Air filter debates seems to come down to:

K & N - best performance, but allows some very fine dust through

Aftermarket Foam - Better performance than stock, but not as good as K & N - BUT does a better job of trapping dirt.

I think the twin air is suppose to be the best of the after market foam.

[speedy400]

I love my UNI:devil -darren

[JB's 400ex]

I had a UNI on my 250x and the major difference between it and stock is that the UNI doesn't have the metal housing inside it that the stock one does. I didn't really notice that much of a performance change but you don't have to mess with the metal part of the stock filter and it seemed a little easier to clean. The foam portion seemed to be a little more porous as well and I am sure that allows air to flow better.

[QuadTrix6]

yea im thinking of going with UNI but i want a noticable performance gain like you get with K&N hmm :confused:

[300exTJjeeper]

you'll see your gains on the dyno with a uni but as a rider I don't you will be able to feel it.