It states you can gain 2 to 3mpg. It does this by giving you a complete fuel burn in the cylinders. I really don't know yet due to just having installed it. You have a couple of ways to set it up. You can set it up for towing where the Propane doesn't start to flow until around 10psi or you can set it up for performance where it comes on at 2psi. Guess which one I have it set on. . I am learning a lot about it now thanks to Quadzilla. I think transmission upgrades are next.
Hope to get pictures in the gallery for those that are interested.