my white wheels have Yokohama Parada Spec 2 but they're pretty worn on the inside, I have no idea how they compare to yours. considering how your pads looked when you swapped them out I'm thinking you might still using the brakes too much, that's why your pressure was so high in the front (this + understeer). When I swapped my pads I was close to 40k miles and had at least 2/3 of life left on them, I don't have a turbo but you know how I drive.
Higher pressure in the rears will help you rotate but at least for me I can rotate fine with all 4 at the same pressure AND the rear sway set to soft which is pretty much your medium setting, also I gain around 4 PSI evenly after a run with the slicks but I don't know what that says about my driving. I don't think you should increase stiffness on your RSB yet, play a little with the pressure first or it might be too much and bite you in the ass. With the Yokohamas I was shooting to have 34 PSI tops all around after a run, for you I would shoot for 32 at the front and 35/36 at the rear. Next time check what the pressure is before your first run to see how much you're gaining, again I'm gaining 4 all around but I would guess you're gaining at least 6 in front