hey, i am new to carbarated engines and I was wondering about that adaptor plate and any mpg gains i'd see. the truck has a 350 engine and a edlebrock 550 4 barrel carbaretour and a holley intake. i think the intake is for a 2 barrel, but it could be 4 barrel. if i bought a 2 barrel carbaretour and this plate (if needed), what type of mpg gains would i see? its getting 12 now.