Well, Eddy has it right here, I tried a run with the vac hose attached and the butterflies working, then the same run with the vac hose removed and the end plugged. Not a huge difference on the flat when gradually accelerating but you can definitely feel it coming off idle. Going up a hill, its very noticeable coming off the start and clear up to 55 or so. I'm not talking about lead footing it, talking about just a normal startup and ease in to traffic kind of thing.

Seer

89LS,90LS,91LS,91LS,95SR,89JeepGrandWagoneer,90JGW,91JGW,92JGW,93RangeRoverLWB,93RRLWB,94RRLWB,94RRLWB,95RRSWB; 90'Dodgezilla' 1-Ton Cummins4x4.