I have a 2004 MXZ 600 SDI w/121" track. It is all stock except dropped one tooth on bottom sprocket (21). I want to get a 136" extension w/ 8" billet wheels relocated. I am also thinking of getting extrovert/introvert drivers. I have 10 tooth drive sprocket stock, but am thinking of going to a 9 tooth. Will the 9 tooth sprocket fit with out cuting the rails? What kind of gearing change will I have to do for the 9 tooth sprocket? Also who has the best products for all this?