There are a few threads on this subject. The front struts got changed for the 14s, specifically the spring perc. So 12-13 has one strut design and 14s are different. As far as I know there are no specific lowering springs for the n/a 14s yet. Steeds has a set for the st and someone recently put st stock springs onto an se, all 2014 parts. A few people have just bought 2013 struts to use the lowering springs available for the mk3. I would search the forums some to get some knowledge on the subject first. Coilovers are a direct swap at a higher price.
Vogtland plug. Lower than pro kit, near stock ride. Love 'em.
I was in on the "research" focusdaily references on 12/13 struts and springs for a 14, that combo works - for the "regular" cars, not ST (I have a 12, but a couple guys with 14's have done the drop that way); no real knowledge of the ST to "regular" swap, but pretty sure someone on here did that with a 14.