I am running a Gibson with a 2 Bros Juice box. There is definately improvement over stock. I road tested different settings and found the base settings to be the safest/all around best. I don't have a fuel/air ratio meter so I can't say for sure. The base settings are meant to be used with a pipe and airbox, which mine will be getting soon. Don't get me wrong, my RZR is pretty snappy the way it is, but I think the cold air box (I'm getting the K&N system) is the missing link to make it really perform. Best of luck.