Last fall I put a dynojet kit and one of those exhaust tips (2inch opening I think) on my 06 kodiak 450, I changed the main jet to a 125. I am having problems after long wide open runs, it backfires, sometime it will do it after just short punches of the throttle, I am no expert at this, but my buddy told me I am running too lean and that I should jump up a size or too on the main and maybe move the clip up a notch, When I say back fire I mean loud bangs. The jet kit calls for a different main when you change the whole exhaust system but no recomendations when changing just the tip?? Any help would be greatly appreciated....Thanks