Michelin has specifically recommended against mixing and matching PSS with PS2 . The difference in performance is significant enough that they are concerned about throwing off the balance of the handling.
They should bring the PSS to your front size, but have not given a timetable for that yet.
I have accepted a new position at Tire Rack and am no longer in the sales department. firstname.lastname@example.org
is available to assist with M3 questions.