I have been running the WR426, Baja designes Vortip, stock jetting with the needle raised one clip (5), just above sea level with great results. Today it warmed up to about 70 and it developed a miss at about 1/3 throttle, got worse as the bike warmed up. It felt lean so I raised the needle, made it worse, went back to stock setup, clip 4 and it improved. Had an EKN needle laying around, put it in on clip 3 with great results. Just tested it on roads, have not been in the woods with it but so far I like it. With an aftermarket baffle I thought the E taper may be to rich. I need some more time with it to see how it starts, hot, cold, plug problems, etc. but so far it rocks.