I took the time last week to install 5th gear from the 2001 WR 426 into my '03 YZ 250. I like my 13/50 gearing for the tight technical stuff we ride, but I hated the low 5th gear ratio that resulted, so I bought the 5th wheel and pinion gears for a WR 426 and installed them in my 2 stroke, resulting in a 12% higher 5th gear for fast sections and connector roads. Now my first 4 gears are nice and close for the trail sections, and I've got overdrive to cruise the fast stuff..........