You mean ST and SVT?the svt and the svt suspension i have heard is the same set up....but the 06+ are just a different shock in the front
The ST has the same shocks and swaybars as the SVT, but has taller and softer springs. The ST has the same nominal ride height as an 05-06 SE/SES, unlike the SVTs, which were lower. However, I'm not sure how the ST's spring rates compare to an 05-06 SE/SES or an 07+ Focus- I just know they're softer than an SVT.
BTW I haven't looked into the prices because I don't have to deal with the 06+ suspension issue, but I agree that you should consider piecemealing the shocks, springs, and swaybars rather than buying the SVT kit and the adapter kit.