I've got a little less than 500 miles on my 05 WR450 and have been doing lots of tuning. Started immediately removing AIS, adding PMB exhaust insert, YZ throttle stop, pulling snorkel, ZipTy and JD jetting kit, blue #3, 170MJ. It immediately started better, barely needs choke and ran pretty well. After putting a few miles on it I wanted to work on the slight bog so I opened up the airbox more, put in a #40 leak jet and dropped to 168 MJ to offset the airbox. I also licensed it so I was getting some street time. The bog seemed to be better but I then got a very annoying surge at <1/4 throttle. I read a lot of threads and tried disconnecting the TPS. It completely removed the surge but I had a very flat low end so I plugged it back in. I just finished putting in red needle, 5 clip, going back to 170 MJ and backed out the AP screw 1/2 turn. Surge completely gone and no bog at all! It's running smoother than it ever has so I am going to try to convince myself not to tune anymore.....oops forgot, I HAVE to check those valve clearances!....after that only riding! Thanks for all the threads and good luck Steve Clark in you search for the right jetting!