I'm running a 49T Renthal. Just depends on the riding you are going to be doing 49T is going to give you more low end and take away a little top. The higher # 50, 51, 52...you go up the more low end you are going to get and in return you will loose top end. Hope this helps
NateS posted a topic in CRF450R/RXI have a 09 CRF450R with a Yoshimura RS-4 Ti/Ti I will be running the spark arrestor 90% of the time. My riding style is mostly trail riding and I am a novice. I have some repacking questions. On Yoshi's web site they tell you that you need to repack the pipe after every 8hrs. Has anyone gone longer or not repacked at all and if so have you had any problems? Like loss of power, pipe turning different colors or even damaging the silencer?