Initial impressions are very good for the HFP suspension. I love the stiffer ride, the reduced body roll (it's almost completely gone) and the lowered stance. Sadly, we just went through a cold snap here in Oregon, so we haven't had ideal suspension testing road conditions. I'll definately be making a longer post regarding the HFP suspension in the 2013 Si sedan, but for right now I'll just throw it out there: it fits in the sedan, buy it!
P.s. Oh yeah, I also ordered a Progress 22mm rear swaybar about 3 days ago. It'll go in after Christmas!