I agree with MS's conclusion and will add that increased rocker ratios will open the valves further. This is normally to increase the cylinder fill hence more power. I cannot see how it will increase fuel economy. I would think it will decrease it.

does the seller of the parts tout fuel economy gains?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.