In my 9650 Walker I run the HI inertia cylinder and back beater, both units are made by sunnybrooke and sold now by Deere dealers and pf parts etc, I have noticed considerable gains in fuel economy, Only have one season and cant comment on sample quality as of yet due to poor Kuchar concave last year, this season will be different and the true tests can be made. I would say I save almost a quarter of a tank a day in fuel in wheat.