Sorry, I know this has probably been asked several times. I am trying to learn more about jetting, suspension, etc. I have an '02 YZ426 that was basically bone stock with very low hours when I bought it in Texas last May. I immediately moved to the Vegas area and I have been riding it here in the desert and having a blast. It has run great and I have no complaints with the motor or the way it runs. A friend out here had a DSP Titanium exhaust system with a spark arrestor built into it that he had previously had on his 426 (which he sold), so he just gave it to me. I put it on last week and didn't notice much difference in the noise level. I haven't ridden it enough yet to see if there is a noticeable power difference. In just the couple of minutes I rode it, I seemed to notice an increase in the amount of backfiring on deceleration (I didn't remember having any backfiring before). Now maybe it was just that I didn't have the bike warmed up yet or the temp was colder outside, but maybe I need to re-jet to match the exhaust characteristics better? Incidentally, I didn't re-jet when I moved to Vegas, but the altitude here is about 1150 feet. I was at about 700 feet in Texas. Any ideas? Also, the same guy gave me a weighted flywheel that I am going to try, as I still manage to stall out a couple times during each ride in the desert. Am I going to notice a significant decrease in acceleration?