I have an '02 YZ 426, stock jetting. It came with Ti-4 muffler and Powerbomb header. The bike was hard to start, hot or cold, and stalled frequently. I called FMF, the technician said go fatter 2 on the main (to 168) and 2 1/2 turns on the air screw. That made the bike REALLY hard to start, still stalled, and got some popping and backfiring. So I took the whole system off and went back to stock. The bikes runs perfect w/ stock exhaust and jetting. Now I want that power rush back and I'm considering trying the FMF system again, this time experimenting more with the jetting. Anybody run this system on their 426 and do you have any suggestions?? Help! oh yeah, I ride So Cal tracks and desert. Anywhere from about sea level to 4000' ft elev (approx).