This has been posted before and I have traded emails with Indy and JD. Still the confusion remains. 2003 WR450 with Pro Circuit 496 muffler, gray wire cut, YZ throttle, TPS disconnected. Started with 155/42/stock #4 and the bike had a mid range stutter when snapping throttle from 1/2 to full - roll on was fine Followed recommendations and rejetted to: 168/42/ stock 4th = low throttle, low speed stutter / great midrange and WOT. 168/48/stock 4th = same (little worse) / great mid to WOT 168/45/ stock 4th = same 168/45/stock 3rd = still stutter 165/45/stock 3rd = same 170/45/JD blue #4 = worse 160/45/JD #4 = better but still not right back to 155/42/ blue #4 = same as original. I do not have a clue why this 2003 WR450 does not get the results that everyone else did with the 168/45/#4 jetting. Anyone experience this? Moded bike running better with closer to stock jetting?