I have been using a 52 tooth sprocket for HS and It works great. However lately I have been riding and racing motocross and find it just a tad too low. Overall the 52 T works pretty good, especially on jumps with a short run. There is one straight that has me pretty strong in 5TH. Most people recomend the 50T, but I would like to hear from you who are using the 51T for MX. Also I run steel as they last longer, thoughts on steel vs. aluminum, not intrested in Ti or SS.