I put a backcountry 1.75 track on the 800 dragon 121. I want more low end pull. I have dropped 2 teeth on my 800r and am looking to do the same here. I want to go from a 25t to a 23t sprocket. Does anyone know if i need to change the chain and or lower sprocket?? Any advise/help/experience is GREATLY appreciated! Trip planned for next weekend and would love to try out this set up!