I agree, the FREDETTE RACING chain guide is the way to go. I bout one for my OLD 92 KDX, and then just TRANSFERED it over to my 97. Only replaced the plastics in the guide twice so far. That thing is BULLETPROOF! I ride TOATALLY IN ROCKS also.
I seem to find the 13/49 tooth combination works pretty well for me. Im 6', and 180lbs. I find myself riding in 3rd gear mainly, and that leaves the powerband right at my fingertips.
Tony