Went to an auto x today with the S03's.
My opinion, they suck. I mean i'd love for them to be grippy but right now with their high tread blocks...I was sliding around like it was wet outside. Skated right through a hairpin on my first run out. I took it easier the next 2 runs but they still were super slick.
Stopping is much much much better than the RE370's were, you can just stomp on the brakes and it slows without locking up. That part is cool.
Otherwise I may have to try out some azenis sometime, but I'll need to get some new rims first.
Overall I've found the S03s to be subpar when it comes to driving highspeed and on the Autoxing.
When they are worn in alittle more and the tread blocks are worn down somemore maybe they will figure themselves out.