Nice setup. Well, common sense tells to begin with the softest position and, as you get used to it, change it to harder setting, especially with a rsb. Rear sway would change understeer to neutral-oversteer, so you have to be careful. With fsb you might start with a stiffer setting right away.
Is your fsb adjustable too? I didn't know Perrin makes adjustable fsb... I have Whiteline front, and it improved a turn-un drastically! I am waiting for rear from Whiteline.