I am going to add a K&N filter/outerwear to our 300ex.I am going to rejet using honda jets(cheaper)I am not looking for a huge gain.Maybe a little easier to pull the front tires.I made a post about adjustaing the throttle all the way out and how much it helped.The stock airfilter gets cleaned about every oil change which is about once a month or so.It doesn'rode much
anymore.(nothing at my house does really)
U can see a good pic of our ex at my pic page.
www.angelfire.com/me3/86trx250r

 

www.atvparts.com there 300EX K&N is 19.99 and dennis kirk has khein jets for 3.50 hope i helped you with finding good deals on prices