The rear suspension and body shell are really the only similarities between the two. The turbo outlets are different so the intercooler and whatnot will not fit, the front calipers are a direct bolt on.. but you'll need rotors that are drilled for 5x100 and lines that fit the brembo calipers. The rear calipers will bolt on with adapter brackets .. and you'll need to use the '10 LGT rotors.
The rear suspensions are just about Identical.. as are spring rates f/r. (I have 08 sti springs on the front of my '10 wrx to level it out) .. suspension wise there isn't much that will cross over to make any noticeable upgrade. Sway bars, springs.. etc.. all available aftermarket for a little more and there will be a much more noticeable difference in performance vs using STI takeoffs.