Making a VERY springy strat

[river]

All the strats I love have a tremendous amount of 'bounce' and springyness to them. I try to get this with my builds, and have come close, but not to the extent of the really great ones. So far the variables I've nailed down that improve 'springyness' are:

trem (of course) floating
lighter gauge springs like raw vintage

as well as (not quite as much evidence):
Flatsawn neck, (possibly thinner helps)
vintage style truss rod (again, more flex)
2-post trem (although I prefer the tone of the 6-posts, I think the 2-posts are bouncier)
Stamped saddles that have less hardness like Fender, Raw Vintage, or Wudtone (NOT Callaham)

These will get you a pretty springy strat- is the rest just magic or am I missing some variables?

 

[Cagey]

While the frets don't have anything to do with string tension, a set of polished gold or stainless steel frets makes things feel much more springy because there's so much less resistance to movement.