I need new sprockets and a chain on my KX 250. Should I get an aluminum or steel sprocket for the rear? I was looking at getting Renthal sprockets and a Renthal O-ring chain. Is this a good combo for trail riding? Are the aluminum sprockets pretty tough? This Oklahoma mud stretched my stock chain out in about three or four long rides. Please let me know ASAP so I can get them on my bike for this weekend! Thanks! Matt