AED in Virgina sells more Holleys than anybody--they always tell customers with a hot rod to do the black bushing and two lightest springs--That combo will work with anything from a small cam to a 750 roller--perfect initial and then all in fast--4 speeders may want a tad different with one lightest and one blue but hey...that has always worked good for us--The two heavy jobs they send them out with won't work with anything--WHO at MSD thought that up? Oh well...at least they have a JOB