After riding around since February with my needle jet in the top position as a free way to lean out my '98, I finally decided to take the advice our veteran posters and re-jet my baby. I ordered a 155 main and 45 pilot from Rage Performance and installed them this evening in 20 minutes. I can't believe the difference. This bike absolutely screams on every level. What's more, I really didn't think be able to tell the difference. I am now a believer in this and HIGHLY recommend it to anyone riding a KDX. Thanks to all the posters on this topic. BTW...it's only $20 and 20 minutes 20/20.