If its completely stock it most likely has a 200 mains, and 25 pilots in it. You shouldnt need to rejet it until you start putting mods on it, exhaust, k&n, etc. Unless its running like sh!t, just check your plugs to be safe.
If you are riding mostly dunes i would go with the T-5's over the fmfs. Or if you really want pipes that scream on the top end get some cpi's or rockets. I was whooping other banshees that had T-5's with my cpi's. They were all sh!tting thier pants after I beat them and told them all I have is cpi's and filters.
Its somewhat similiar to the dial a jet system. The way you jet the carb is with the turn of a screw on the top of the carb.
My brother has one on his yfz and hasnt had one problem with it. Runs like a champ! Maybe your friend just had a lemon... I know Dennis Packard makes some quality products and stands behind his products.