I have a 2002 RM 125. Problem is that I can not get any power out of the low end. I went one size bigger on the rear sprocket but still is not enough. I also put a spacer in the exhaust port which helped a lot but I ride other 125's and it is embarrassing to let somone ride mine. It has no low end. I even changed the reeds to a boyseen dual stage that also did nothing. HHHHHEEEEEELLLLPPPPP.