Ok, so i want to do somthing to help with my milage on my truck, what kind of mileage increase could i expect from a dual fuel system on my 302? Would i need a new carb or what? (i have an edelbrock performer now) Or would i be better off with a pure propane system? I want somthing that's cheaper than gas with equal or better milage that costs under like $200. I was told i could assemble a dual fuel system for like $200.